Calathea rufibarba, a beautiful yet rarely grown species with fuzzy, scalloped leaves which are a deep green above and purple below. Certainly a little more interesting than a Spathiphyllum or other similarly-sized plant, this species garners a good amount of attention. Image © In Situ Plants.
Calathea rufibarba, a beautiful yet rarely grown species with fuzzy, scalloped leaves which are a deep green above and purple below. Certainly a little more interesting than a Spathiphyllum or other similarly-sized plant, this species garners a good amount of attention. Image © In Situ Plants.
Anthurium superbum, a species with beautiful bullate leaves that thrives in bright indirect light. Image © In Situ Plants.
Anthurium superbum, a species with beautiful bullate leaves that thrives in bright indirect light. Image © In Situ Plants.

There are an estimated 400,000 species of plants on earth. While this includes species such as giant marine kelp, leafless parasitic plants, and a slough of other ones not ultimately suitable for indoor cultivation, there are a significant number which will do quite well in an interior setting provided a few basic conditions are met, and certainly more species than are typically seen indoors.

It seems then a disservice to our clients, our own industry and plants in general that most companies seem to prefer to play it safe with the tried-and-true varieties that we’ve all become so accustomed to seeing. They’re about as common as dirt, as the saying goes, and, besides the fact that they (hopefully) have been grown as premium interior specimens and not hastened out the greenhouse door in the fashion of so many of the houseplants sold to the consumer market (the subject of another forthcoming post, I’m sure), there’s not really much to differentiate them from the plants that people are growing on their own at home, or at least that they’re so used to seeing everywhere that they don’t even notice them anymore.

It’s a disservice to clients because, while presumably done with good intentions in order to spare clients the sight of an ailing plant should anything go awry (most of these are very tough to kill [or at least they die slowly and relatively gracefully], and perform fairly predictably), it doesn’t really deliver a tremendous amount of value to the client: certainly they will get the physical benefits of having plants indoors (these benefits were touched on in this post), but the aesthetic and biophilic benefits of plants seem to me somewhat dependent on the plants being engaging and actually noticed, instead of looking like furniture as they so often do. And why have something commonplace when something extraordinary is just as much cost (on their part) and effort (on our part)?

It’s a disservice to our industry for several reasons. As I noted above, to the untrained eye these species, even if they’ve been better grown, look nearly indistinguishable from the ones that can be bought for a pittance at a big box store or wherever; it is challenging to justify the price point for them when someone thinks that they’re the same as the ones they saw for a quarter of the price up the road, even if they get the whole spiel about quality, etc. The other side to this is that many people grow these plants in their home themselves; why, then, would they pay us to do it? Yes, we can do a much better job (hopefully!), but it’s just another aspect we need to justify to the customer. Granted, there are some situations (extreme low light, for example) where only the bulletproof plants will do, but in most situations there is likely something more unique that could be used.

Lastly, it’s a disservice to plants (not that they care): what better way to share a passion for all things green than to try and show the public as much of that world as we can? There’s just so much out there that it seems strange to restrict ourselves to the commonplace when we’re in the business of bringing life into our clients’ spaces; certainly showcasing the extraordinary biodiversity that the plant kingdom has to offer is an effective way of doing just this.

Plants are able to do so much for us, and technology now makes it easier to keep species with particular requirements happy without any additional work (the Calathea above would certainly be trickier without the sub-irrigated planters it’s in; it’s relatively easy to grow so long as it doesn’t go dry). Vertical gardens allow the perfect growing environment for plants so uncommon in cultivation that they don’t even have a common name; the combination of ample water and high humidity makes a huge variety of plants available to the vertical gardener. What a shame then to see so many large, high-profile projects populated by pothos and other common plants when the whole of the tropics could have been the designer’s oyster.

In Situ challenges all in our industry (growers, local wholesalers and interior landscaping firms) to venture off the well-trodden path of Dracaena and Schefflera and step into a world rich in plant species which can grow our industry and the public’s love and appreciation for plants indoors.

Anoectochilus formosanus, a beautifully-patterned small species of orchid which grows terrestrially in leaf litter in its native habitat, and which loves the moist humid surroundings of a terrarium. Image © In Situ Plants.
Anoectochilus formosanus, a beautifully-patterned small species of orchid which grows terrestrially in leaf litter in its native habitat, and which loves the moist humid surroundings of a terrarium. Image © In Situ Plants.
The tropical understory; a wealth of interesting species often better suited to the confines of the humid terrarium than the oft-toted succulents. Image © In Situ Plants.
The tropical understory; a wealth of interesting species often better suited to the confines of the humid terrarium than the oft-toted succulents. Image © In Situ Plants.
Mosses, to me, are some of the most lush and beautiful plants one can grow, and they do best in a humid terrarium. Image © In Situ Plants.
Mosses, to me, are some of the most lush and beautiful plants one can grow, and they do best in a humid terrarium. Image © In Situ Plants.
Peperomia prostrata, a long-standing terrarium favourite which is also quite cute and succulent-looking. Image © In Situ Plants.
Peperomia prostrata, a long-standing terrarium favourite which is also quite cute and succulent-looking. Image © In Situ Plants.

You’ve likely read me hint before about my disdain for the current craze in succulent plants, and succulent terrariums in particular. Don’t get me wrong: I’m glad to see an interest in plants in general, and I have nothing against the plants themselves, really; there are a lot of interesting plants that are classified as succulents, displaying a huge variety of shape, colour, and texture, which I suppose is the appeal.They have a reputation of being hard to kill, which I’ll admit is partially true; they grow easily enough when conditions are favourable, and if they are not, most of them are at least slow to decline if pretty much left alone, though improper care can hasten their end, especially via overwatering. They are inxepensive, though (particularly the cute young plants that florists and the like get in), and so are easy to replace when one knocks off.

But are people satisfied with this? Isn’t the whole thing about keeping plants to try and keep them alive and doing well? I’ll readily admit to having killed a plant or two in my time (not usually for lack of trying), but one of the first things I think about when I find a plant I like the look of is whether it’s suited to my growing conditions, and, for me at least, most succulents are patently not. They require (for the most part) very bright light, which is an immediate turn off for me personally, and should be for most people I meet who profess to be ‘really into succulents right now’, most of whom don’t have a window with decent exposure, let alone the solarium or greenhouse that would really allow these plants to do their thing.

These plants end up being stuck in a seashell, a shot glass, or some other kitschy place, or worse yet, a terrarium, where conditions are not exactly optimal; these plants are adapted to arid regions, and most require very bright light, free-draining soil and good air movement to do well, and without special considerations these can be very difficult to achieve in a terrarium environment, which are by design retentive of moisture and humidity.

Seeing as how one might have a glass vessel around after succulent disasters of one kind or another (if not, they’re readily available from many stores now in various shapes and sizes, though of course any glass or otherwise transparent container will do, really), why not give one a go again with plants that are perfectly at home therein? The really nice ones (such as the orchid to the right) can take a little digging to rustle up, but there are many fine species which can be found without too much trouble and with which one can have some rewarding success with terrarium gardening. Because the terrarium should really be a less intensive and more problem-free way to keep plants indoors; soil moisture is held much longer, so issues with forgetting a watering will not be as severe, and most plants will benefit from the extra humidity and reward the grower with larger, vibrant-looking foliage while at the same time avoiding the many foliar maladies that come with dry indoor air.

This was the original purpose of the terrarium, after all; Wardian cases have been around since the Victorian age as a way of keeping exotic tropical plants alive indoors, which was the style at the time. Ferns and the like were and are appreciative of the shelter provided by these glass enclosures, and we now have better technology which allows us to have seamless (and leadless!) glass enclosures for these plants, which makes them all the more attractive while still being quite functional.

What are the prerequisites for a good terrarium plant? First and foremost the plant needs to be adapted to the conditions approximated by a terrarium, which typically consist of lower light, consistently moist soil, higher humidity, lower air movement and limited space, though all of these variables can be controlled to some degree. Fortunately there are many plants who are right at home in such an environment; think of the tropical forest understory, where the light is dim and the air and soil are often very damp indeed. Many species can be found either growing directly on the ground or else epiphytically on the lower portions of trees, and these are often the best suited for terrarium life.

There are plenty of blogs and articles out there that list suitable species, so I won’t bother with one here. Be wary, though, as some of these lists are not entirely well thought out and some of the listed species may eventually grow quite large (relatively speaking); when starting out, working with a larger container will help keep things manageable without needing too much maintenance to keep things from being cramped. Do a little research and find out the maximum size of any prospective species and it will save you trouble in the long run. There are a great many true miniature plants which will stay small for their entire lives, but they are often not available through most retailers, who instead often sell juvenile plants in small pots because they’re cute and inexpensive. An alternative might be creeping or stoloniferous plants, for example, like Pellionia, Pilea, Episcia and others, which are pretty easy to find; their size is very easily managed, for they stay low to the ground and need only be trimmed when they start climbing the walls of the terrarium. There are many upright plants which will stay reasonably short in stature that pass through the garden centres and florists’ often enough, too, so familiarize yourself with a few of the plants from the terrarium-friendly plant lists beforehand and keep your eyes peeled.

There are in fact whole enterprises geared towards selling terrarium-friendly plants (though not so much in Canada, unfortunately); in the USA, Black JungleJosh’s Frogs and Glass Box Tropicals are three that are very popular amongst dart frog hobbyists, who build elaborate natural planted enclosures for the species they keep in captivity. Not all of us have access to these places, of course, but their stock lists do serve as a handy reference for plants amenable to the terrarium environment.

A couple tips on setting up and maintaining a terrarium: first, use good quality soil for your terrarium and I guarantee better success than using the dirt from the garden centre (I’d written a little bit about terrarium soil near the bottom of this post): one that allows better aeration and increased longevity will make plants much happier over the long term. And keep up on your watering, but notice that a little water will go a long way; one of the benefits of a clear container is that you can watch the water you apply migrate and spread out into the soil. Do this once or twice while paying attention and you’ll get a sense of how much water it will take to keep things just right. And if you’re a heavy-handed waterer by nature, do not despair; there are plenty of plants that don’t mind wet feet. Plants sold for aquariums, for example, are often riparian species that will do marvelously planted in consistently moist to wet soil and kept humid, and the selection in the trade now is better than ever.

Second, keep that thing out of direct sunlight, especially if it’s without any ventilation holes; if you’ve ever been in a greenhouse on a sunny day you’ve experienced the greenhouse effect, where heat is trapped and accumulates within. This effect works within the terrarium, too, and plants inside can easily be cooked if temperatures are allowed to become extreme. If you’ve picked the right plants, bright indirect light should be the most you’ll need, and many will tolerate deep shade fairly well.

Third, do your homework! If you learn a thing or two about a particular plant’s origins and habitat you’ll be able to make an educated decision on whether it’s a good candidate for the terrarium or not; a simple search online with the species name appended with the word ‘habitat’ will bring up a fair amount of information in most cases. Even cultural tips such as ‘enjoys high humidity’, ‘keep out of direct sunlight’, and ‘keep moist but not wet’ are all valuable clues to the suitability of the prospective species. Knowing your plants a little better also increases the richness of keeping them as a hobby, I feel, so don’t be afraid to nerd out a little.

If you are hellbent on succulents and not having much luck with them inside glass containers, perhaps a dish garden may be a better direction to go for your diminutive landscapes; this will allow for better air movement and the option for higher light in order to achieve greater success with these plants. And of course all of this is not to say that a succulent terrarium is impossible; I’m sure there are people out there who can pull it off (long-term, I mean; anyone can stuff some plants in a jar and put a photo of it on the internet). But the terrarium environment is really best suited to tropical species which will respond positively to those conditions, and if it’s the particular form of succulents that appeals to you, there are many other plants which are succulent-looking in nature but which do hail from tropical forests. Many Peperomia are quite succulent, and most are very well-suited indeed; P. prostrata above has to be one of my all-time favourites. There are some caudex-forming epiphytes such as Mymecodia and Hydnophytum (which are profoundly interesting in their own right due to their mutualistic relationship with ants in nature; read more about that here) which are delightfully rotund at the base and often a little spiny, Cryptanthus and other bromeliads certainly conjure the rosette forms of Echeveria or Haworthia, and the list goes on and on, so give something new a try and have another look at the terrarium; there’s so much out there waiting for you.

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Tungahua I - Bosque Protector Los Cedros

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Trogon Creek - Bosque Protector Los Cedros

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Amanecer Cerca del Observatorio - Bosque Protector Los Cedros

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Clearing - Bosque Protector Los Cedros

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Aves en el Bosque Secundario - Bosque Protector Los Cedros

I thought that there might be some interest in these, and they’re certainly not doing anyone besides myself much good just sitting on my hard drive. When I last had the pleasure of visiting the tropical forest I recorded many, many hours worth of soundscapes from different areas of the Bosque Protector Los Cedros, a biological reserve in Ecuador covering 17,000 acres of mostly untouched wilderness in the lower part of the Chocó biogeographic region, one of the world’s biodiversity hotspots and home to a staggering number of species of flora and fauna, many endemic to the region.

Below are several recordings, all about an hour in length. They were taken from several locations and form something of a picture of this type of forest in the middle of the (relatively) dry season; though life doesn’t seem to slow down much in the rain there, it certainly becomes more challenging to record it well. My efforts at makeshift umbrellas made of Anthurium leaves were enough to protect my equipment from the many downpours, but the acoustics left much to be desired. All of these recordings were made with me present, perched a little way further down the trail but still within eyeshot of the area so that I could attempt to document the wildlife I was recording (I must have looked positively ridiculous flipping furiously through the field guide The Birds of Ecuador, which contains something like 1600 species, after some tiny hummingbird or another).

I will unabashedly confess that this area of the world is what sparked my interest in plants, and I believe that In Situ has come into the interior landscaping industry directly from these forests, with our boots still muddy; our interest in working with more unusual and exotic species, replicating natural habitats, creating impromptu natural history lessons and trying to recreate indoors that feeling one gets when surrounded by a forest almost violently alive and brimming over with some of the most amazing plant species on earth is a direct result of this early exposure to the rainforest of South America.

Mostly tranquil, sometimes raucous, often hilarious (although maybe you had to have been there), these recordings (to me, at least) capture much of the feeling of being alone in these primeval forests; so lush, vibrant and vigorous, the plants seem to grow visibly as you watch them, and there is an abundance of life everywhere you rest your eyes. I hope that they have some measure of transportive effect: take them for a spin and let me know what you think.

If I hadn’t temporarily lost my notes I’d use the space here to name the goodly number of bird species one can hear in this recording; when they turn up I will add them. The avian fauna makes up a large percentage of the readily visible creatures one can see when walking (or in this case, sitting) the trails at Los Cedros. (I should say relatively visible; even the brightest coloured-ones are somwhat cryptic in the riot of life that is this type of forest.)

If you have this recording on at appreciable volume though a decent set of speakers you may notice a dull booming sound, which I didn’t know what to make of when I’d heard it out there. It wasn’t until I got back to camp and heard the news that the Tungurahua volcano near Baños (nearly 200 kilometres away) was erupting did I put two and two together.

This recording was named after the bird which can be heard calling beginning at about twelve minutes into the recording; a beautiful bird which I had seen infrequently but had never heard call before I captured it here.

Water is at the heart of this forest, and indeed this reserve’s mountain streams and massive rainfall serve as the principal watershed for the surrounding communities, which are noticeably hotter and dryer than even a little ways up the hill.

El Observatorio is a small open space atop a hill on the ridge that overlooks Los Cedros. Perched at about 2100 metres, it’s a great place to sit and, weather-permitting, look out over the great untrodden wilderness below.

It’s a bit of a hike to get there, much of it along the sopping-wet ridge where is seems always to be raining or have just finished raining; epiphytes abound, and it’s a great place to find orchid species, among them species in the genus Dracula, of which several are unique to the area.

This recording was taken at dawn after having spent the night on said ridge with a couple other fellows and a prodigious amount of rum. Dawn was certainly not as painful as it could have been had I woken up elsewhere, as I’m sure you’ll agree after listening.

Empty space is somewhat hard to find there, but I was able to find a clearing at set up shop for a few hours, which is where this recording was taken. By the way, the white noise that’s present more or less in all of these recordings is the sound of the river, which was something of an annoyance, but easily forgivable.

This is a pretty minimal recording, really, (with the exception of the one or two parrot-flock flyovers) but I feel like you can hear a bit of tension; it was threatening to rain (again) for its duration. A few of the forest-edge bird species make their appearance here.

Another recording taken just after dawn in an area of more secondary forest, where epiphyte density is a little lower and where sound seems to carry a little better. If you’ve ever been up and about at dawn (couldn’t blame you if you haven’t) you know that it is a busy time for our feathered friends, and is a general changing of the guard in the tropical forest from the night to the day shift, so one tends to hear a good solid mix of different creatures at this time, from frogs to insects to monkeys and lots of things in between.
Epiphyllum oxypetalum, grown here epiphytically on a date palm, and showing a huge flush of flowers that can reach nearly a foot wide. Image © Kiwoncello; image retrieved from Compagna del Giardinaggio.
Epiphyllum oxypetalum, grown here epiphytically on a date palm, and showing a huge flush of flowers that can reach nearly a foot wide. Image © Kiwoncello; image retrieved from Compagna del Giardinaggio.
A small colony of young Sinningia pusilla, growing comfortably in a 2" nursery pot, with blooms nearly the size of the plants. Image © In Situ Plants
A small colony of young Sinningia pusilla, growing comfortably in a 2" nursery pot, with blooms nearly the size of the plants. Image © In Situ Plants
Columnea microphylla being shown at a Toronto Gesneriad Society meeting. Image © The Toronto Gesneriad Society; image retrieved from their website.
Columnea microphylla being shown at a Toronto Gesneriad Society meeting. Image © The Toronto Gesneriad Society; image retrieved from their website.
Stapelia gigantea, shown here with a ridiculous amount of huge stinky flowers. Image © gardenmaniac; image retrieved from the Dave's Garden website.
Stapelia gigantea, shown here with a ridiculous amount of huge stinky flowers. Image © gardenmaniac; image retrieved from the Dave's Garden website.
Lepanthes telipogoniflora, a tiny species with a huge name and a huge flower. Image © Thomas; image retrieved from the Species Specific forum.
Lepanthes telipogoniflora, a tiny species with a huge name and a huge flower. Image © Thomas; image retrieved from the Species Specific forum.

What follows below is a short list of several species that have a wonderful aspect to their morphology; they just happen to have ridiculously large flowers, either in fact or in proportion to themselves (perhaps it’s the same as in ants and other smaller creatures, which are able to lift many times their own body weight, that only smaller plants can grow a flower that is larger than the rest of the plant). These are all species that can be grown indoors, though some are more challenging than others.

Epiphyllum oxypetalum and related species

One of the many plants with the common name ‘queen of the night’ (and also known as ‘orchid cactus’ ‘Dutchman’s pipe cactus’ or ‘night-blooming Cereus’), E. oxypetalum is an epiphytic cactus native to Mexico and a good part of Central America. It produces dinner-plate sized white flowers that open for a single night and are heavily scented. This plant grows easily enough in a pot or hanging basket, and will bloom well enough indoors if care is up to snuff. It is pretty rambly by nature, and can get awfully large if you give it room, though it is easily pruned to shape, and at least the stems are spineless, which makes brushing past one in a tight space not as uncomfortable as it might be with some of its close relatives.

Sinningia pusilla

I know that terrarium gardening has been a fad of late, but I fear that the concurrent popularity of succulent plants may cause people to be frustrated by limited success with terrariums (this being for the simple fact that succulents by their very nature are not good candidates for terrarium culture); more on that whole thing later, but in the interest in promoting terrariums as an actually quite easy way to grow plants and have them do well (read grow well and flower), I would like to make Sinningia pusilla the poster child of terrarium gardening.

This species has everything to recommend it; they are adorably tiny (leaves are around 3/8″ long), have fuzzy, somewhat iridescent foliage, and, best, throw huge (relative to the plant, at least) pale tubular flowers. They self-pollinate and are quite prolific, able to quickly start colonies of seedlings that form an attractive ground cover. They also are quite easy to grow if provided with one thing above all: humidity. Enter the terrarium; given the added humidity, these plants will flourish when the soil is kept reasonably moist; if allowed to dry too far or too long, they will go dormant, reducing themselves to a tiny tuber to await the return of more favourable times. They are also fairly undemanding of light, which sets them worlds apart from succulents and other plants commonly toted for terrariums.

Columnea microphylla

This species and S. pusilla above both belong to the family Gesneriaceae, which contains a great many species well suited for growing indoors, of which the ubiquitous African violet is a familiar one. Columnea is a large genus with much variety, but Columnea microphylla has to be one of the most impressive. Again, it is not the largest plant (the one to the left looks like it’s in a 3″ pot), but the red flowers absolutely dwarf the leaves.

This species makes a great hanging basket plant, and the pendant stems will trail downward and show off their freakishly large flowers. This one will need a fair bit more light than the Sinningia above to bloom well, but won’t take up much space in a sunny window.

Stapelia gigantea

A first glance of the foliage and you might want to call this one a cactus, but not only is it not one of those, in fact its more familiar relatives are Hoyas, the tropical vines native to Asia commonly grown as houseplants, as well as the common milkweeds here in Ontario which are the chief food supply for monarch butterfly larvae. Stapelia is a genus restricted mostly to southern Africa, and so need a cooler rest period over the winter. making them a good candidate for a bright but poorly insulated bay window in a century home, say. The flowers can be up to a foot across, but have the unfortunate characteristic of reeking of rotting meat in order to attract flies, which are their natural pollinator. A beautiful plant to be sure, but I suppose not for the faint of heart; perhaps I should recommend that this one be brought outside in summer.

Lepanthes telipogoniflora

I’ve saved the best for last, and this little one is, to me, one of the most incredible orchid species out there, despite being only a couple inches across.

Lepanthes telipogoniflora is a diminutive orchid endemic to Colombia, where it grows in some of the wettest rainforest on earth (one spot once reported 43 FEET of rain in a year), which gives us a pretty fair hint as to how it should be kept in cultivation. Alas. I have personally killed this plant (twice); it understandably does not take to drying out in the slightest, and small plants are completely unforgiving. Enter again the terrarium; many people grow this plant successfully in those little round glass hanging terrariums that are quite easy to find these days, and as long as they’re kept happy (you’ll know it is so because the plant won’t be dead) they will bloom pretty consistently, with the flowers being relatively massive and at least the size of the plant in younger specimens. Another important cultural note is that they, as are many of the Pleurothallidinae orchids, are intolerant of hard water, and require rain or otherwise filtered water to do well. This species is, so far as I know, not produced by any Canadian orchid nurseries (presumably because of the aforementioned cultural challenges), but is brought in by Ecuagenera when they attend regional orchid shows here, and presumably by others as well.

This list of huge bloomers is by no means exhaustive; in fact, I’m sure I’ve only scratched the surface. If any other plants fit the bill, list them in the comments below!

 

If you’re unfamiliar with the chemical reaction above, then you may also be unfamiliar with the fact that life as we typically tend to think of it would not be possible without plants.

Photosynthesis is responsible for the capture of solar energy that in turn powers nearly all life on earth: everything we eat is either plants, or other animals that formerly ate plants (or that ate other animals that ate plants). Plants absorb sunlight and convert it into chemical energy which is stored within the plant for its own uses; we eagerly exploit this by consuming them and thus the sum of the solar energy they’ve stored. Good deal for us, bad deal for the plants (not that they seem to care).

There are not many other ways to capture and metabolize energy in this way, save chemosynthesis (which is why I need to keep referring to ‘almost all life’ above, which, while definitely less dramatic, is more accurate, as there are organisms which are able to capture energy from chemical reactions, most notably in deep-sea communities colonizing hydrothermal vents, and so have no need of sunlight). So plants really are the foundation of nearly all life on the earth.

And not just regarding energy, either. Though a bit more oft-toted, the fact that plants maintain the planet’s oxygen levels is equally prevalent. This does bring up the subject of conservation, but I can save that for another time. I will add in a shameless plug, though, that plants indoors will raise local oxygen levels and just generally improve the air quality indoors. You can read this post for more information if you like: Plants at Work: The Science Behind how Plants Improve Life Indoors.

For anyone interested in the equation who doesn’t understand the chemistry, basically the plant takes 6 molecules of carbon dioxide and 6 of water, and splits these to create free oxygen (which is released by the plant), and a few other goodies which combine with the solar energy captured by the chlorophyll in the plant to create carbohydrates (the C6H1206 in the equation above) which contain that solar energy. Pretty simple, but critical to life on earth.

It’s a little humorous to me that our industry (speaking very broadly here, of course) provides, in a manner of speaking, a product that no one can live without. Maybe that’s why everyone tends to like plants so much: I’ve met many people indifferent to them (and have changed a few minds there), and many more people who love them but can’t seem to stop killing them (and I can only hope I’ve helped a bit there), but have never really met anyone who’s said that they actively dislike plants (except maybe recent victims of poison ivy or the like). Maybe it’s a stretch to assume that we as a species are that aware of the inexorable connection we have with the rest of life, but for whatever reason the biophilic instinct is certainly alive and well.

High-quality peat moss: note the large, fibrous-looking pieces. This is Lambert`s AFM soilless mix. Image © Lambert; retrieved from their website.
High-quality peat moss: note the large, fibrous-looking pieces. This is Lambert`s AFM soilless mix. Image © Lambert; retrieved from their website.
Low-quality peat moss: a photo of the dark, small-particled stuff that is sold at the consumer level. Image © unknown; retrieved (strangely) from LA Readers blog.
Low-quality peat moss: a photo of the dark, small-particled stuff that is sold at the consumer level. Image © unknown; retrieved (strangely) from LA Readers blog.
It's pretty tough to dispute the effect of a perched water table when it's captured in photos like this. Image © unknown, retried from The Garden Professors Blog

I had promised back in one of the parts of Watering 102 (see parts onetwo and three of that massive tome here) to write a little about growing media, and how to select or make one yourself in order to grow great plants. There are several aspects to consider that will help you make the best choice as far as what to use, and a lot depends on the type of plants you grow, how heavily/frequently you water, and environmental factors such as heat and humidity.

We’ll get this out of the way first, though: don’t ever call it dirt. Dirt is the stuff that ends up under our fingernails, and what we sweep off the floor. It’s something of a derogatory term, I feel. This is actually one of the first things that got drilled into us at horticulture school, and it stuck. We are all better off calling it soil, though even this is a bit of a misnomer, as what we typically use for indoor applications is a soilless growing media containing mostly organic material and no true mineral soil, such as you’d find in your backyard. ‘Soilless growing medium’ is a bit of a mouthful, though, so soil will suit our needs here.

First and foremost is peat moss. This material is partially decomposed sphagnum moss which comes in varying grades and qualities, and is the major component of most mixes, from the dusty garbage they sell you at the garden centre to the tried-and-true stuff used to produce countless acres worth of ornamentals of all sorts. When of an appreciable quality, it is best described as ‘fluffy’, and if you compare qualities side by side, the difference is striking. Quality peat is light in colour and feel and has varying larger particle sizes, which allows for good aeration. It also has a good water-holding capacity without becoming mud when very moist. It is relatively long-lived, though it does degrade over time. The other stuff is dense, with mostly small particle sizes, and is basically a more decomposed version of the nice stuff (being dredged from deeper in the peat bogs from which the material is drawn [the sustainability of which practice may come up in a future post]). It does become mud when you try and water it. It’s basically garbage, because it becomes a real challenge to ensure that a plant’s roots are able to absorb enough oxygen to keep from dying.

It’s important to make sure if you’re going to be purchasing straight peat moss for use in your own recipes that it is buffered: peat moss on its own is highly acidic (and is used as an amendment for acid-loving plants such as plants in the Ericaceae family such as blueberries), and bufffering will raise the pH from 4 or so up to about neutral (7), which is where most species will be best suited.

There is an alternate material to peat moss made from the husks of coconuts, called coir. It also comes in differing types, from roughly chopped husks to finely ground fibres. It is longer-lasting than peat, and also is less hydrophobic, meaning it will more readily absorb water when it is dry, which is handy. One serious issue is with the source of this material: as coir is processed it is often washed in seawater, and unless it is thoroughly cleaned can impart some serious saltiness to one’s plants, with the obvious devastating effect that you might expect. It is important to only buy this stuff from a reputable source (hydroponics stores usually stock it), or to process it yourself in order to ensure it is fit for use.

Perlite is usually the other component in soilless mixes. This is an expanded volcanic mineral which imparts greater aeration and water-holding capacity to the mix. It is not fertilizer, nor is it styrofoam, or anything else I’ve heard it being referred to as. It comes in varying sizes, with larger pieces being used for things like bark-based orchid media. It is admittedly ugly and unnatural looking, and has the bad habit of floating to the top of the container when watered heavily.

On that note, bark and sand are two more materials which can be found in some mixes, also in order to create more room for air in the growing medium. Sand is a bit outdated, but it’s cheap, and can be found in the dirt that’s marketed for cacti and succulents. Bark is more useful, but does break down eventually. Vermiculite is another mineral that is sometimes also used for enhanced water retention and aeration porosity. Other materials in specialty mixes are long-figer sphagnum moss, which is the undecomposed version of peat moss (you’ve probably seen orchids grown in this), and which greatly increases the water-holding capacity of a mix, tree fern fibre (a durable material derived from tropical tree ferns which creates a really nice open mix for things like epiphytes) and charcoal, which has little value past increaasing aeration porosity and its longevity.

So with that out of the way, basically what we’re looking for is a medium that provides the right mix of water-holding capacity to air-holding capacity for the type of plants we wish to grow, and for the amount of water we are applying. A decent basic soilless mix such as Berger’s BM6 contains about 75% peat to 25% perlite, and I’ve grown an extensive array of plants in this without any amendment. It can hold a lot of water if you let it, but it’s also a very good mix for keeping lightly moist, as it does drain quite freely. Again, if you let it go bone dry it will be difficult to rewet due to the hydrophobic nature of the peat, so bear that in mind. A lot of growers of gesneriads advise amending a mix like this to more of a 1:1 peat to perlite ratio, and while there’s definitely no harm to it, I’ve been able to grow most gesneriads I’ve worked with in just the basic mix by simply avoiding overwatering.

If you are heavy-handed with the watering can you may benefit from amending your mix, but there is such a thing as too light a mix as well. With increased aeration comes reduced water-holding capacity, and less than adequate watering can quickly lead to dessication. High temperatures and low humidity can also contribute to a more rapid drying of the media, and in some cases it may even be beneficial to have less aeration porosity in your mix: there are some unforgiving plants which are goners after they dry out even once (you’ll notice that the growing media of most ferns you see available, for example, do not even contain perlite).

How you use the mix will play a large role in how it performs. One of the most important things that needs your attention is that the media loses its functionality when it is crammed and forced firmly into the pot. While it does seem to hold a plant in place very well, this basically reduces all of those nice large spaces between soil particles that would ordinarily hold air, reducing them to a size that is then only capable of holding water. That’s bad news for plant roots, and maybe a bit of a slight to the hardworking folks who spend all that time developing and optimizing their professional growing media for the perfect aeration porosity. Slightly overfilling the container with soil and them watering the plant in gently but thoroughly will do wonders for securing the plant as the soil settles into itself, and the integrity of the mix will be preserved, allowing you (and of course, your plants) to take full advantage of its properties.

When watering these mixes, particularly when the container has been freshly planted, it is best to use a watering can or hose with a breaker in order to keep from disturbing the soil surface: in time, the soil’s microbiology will colonize the media and produce exudates which hold everything together nicely and make it easier to throw water on without having to worry too much about taking the extra time (good news for professionals).

Remember, too, that if you’re using any organic material at all, it will eventually decompose, and the soil will need to be changed. I won’t go into repotting here, but if you seem to have problems that could be explained by overwatering even though you’ve been doing everything the same way for a long while, decomposition of the media may be the issue.

A note on terrariums, particularly ones which actually have half a chance of success and aren’t just a few succulents thrown into a glass bubble because someone saw it on Pinterest (yes, I have a serious hate on for the current terrarium craze; so much so that I’ll likely rant aout it in another post): I want to draw your attention to the fabled ‘ABG mix’, one of a few substrate recipes whipped up by Atlanta Botanical Gardens for plants in their collection. This stuff has really caught on in the vivarium hobby (basically a planted terrarium that houses creatures like lizards or frogs), as it has perfect drainage and very long life, which are two things that can plague a planted glass enclosure. The mix commonly used is as follows:

1 part peat moss (or coir)

1 part milled sphagnum moss (ground or chopped long fiber sphagnum moss)

1 part fine horticultural charcoal

2 parts tree fern fibre

2 parts fine bark

You can have many years of enjoyment with this mix in the warm, humid conditions of a terrarium without it breaking down, and another bonus is that it looks way more natural than a peat/perlite container medium. If you play around with the ratios you can also create a great mix for houseplants that also resists decay and can allow you to go for quite some time without needing to repot due to substrate decomposition.

OK, one last thing about container media that has to do with drainage. There is an adage that many of you have no doubt heard about putting pot shards, gravel, or other material in the bottom of the container before filling with soil to allow for better drainage. This is a useless and counter-productive practice, and here’s why: because of the way water interacts with itself and with soil particles (cohesion and adhesion, respectively), it will not move readily from an area with small spaces between particles to one with large space between particles. The top of a layer of gravel or whatever is pretty much the same to water in soil as the bottom of the pot, so basically all you’re doing is eliminating valuable real estate for plant roots, and potentially creating conditions in which too much water is held in the soil because it’s not draining properly. Use the same medium throughout the container and you will generally have better results.

The photos to the left illustrate perfectly the effect of having a larger-particled substrate over a finer-particled one: the water distributes itself throughout the top layer and does not move into the layer below until fully saturated. The myth of drainage is one of those many things in horticulture that has just been repeated so often everyone thinks it must be true (and have a look at the comments on the page I grabbed the image from to see the type of stubbornness to change that is basically rampant in the scene, professional and amateur alike. This was another of the first things that we learned at school, and we did a whole whack of labs that really drove the point home for us.

So there it is, long-winded as ever. The takeaway points, I guess, are: don’t buy shitty quality soil, don’t cram it into the container, don’t bother trying to improve drainage with other materials, and don’t put succulent plants in terrariums.

Figures 1 and 2 from the bedding plant study linked above, showing increased flower production and less wilting in plants grown with less available phosphorus.
Figures 1 and 2 from the bedding plant study linked above, showing increased flower production and less wilting in plants grown with less available phosphorus.
Remember, the job of the fertilizer company is, first and foremost, to sell fertilizer. Properly managing plant nutrition is the responsibility of the grower.
Remember, the job of the fertilizer company is, first and foremost, to sell fertilizer. Properly managing plant nutrition is the responsibility of the grower.

I can’t dispute that phosphorus is an essential element in plant growth: it is present in every cell, and is directly involved in many processes in the plant, including, energy generation, respiration, nitrogen fixation, and most importantly photosynthesis. A plant can’t do much without it. There are a lot of old ideas, though, that are repeated in the horticultural industry, despite the fact that they have been obviously disproven. In the interest of attempting to dispel the dogma and disseminate some valuable insight about how plants actually make use of the phosphorus that we provide them (or, more importantly, how they often don’t), what follows are a few points that hopefully will help professionals and amateurs alike choose the best fertilizer for the needs of their plants.

Note that I put the word ‘interior’ in the title, hoping to imply that the plants I’m discussing are growing in a soilless growing mix indoors, and not in the ground: that’s a whole other can of worms, and the concepts here will be greatly simplified without having to worry about it. We’re working with basically a blank slate here, nutrient-wise. It’s also easier for us here in Toronto because the water is fairly low in minerals save the bloody bicarbonates, which I’ll likely talk about at a later time.

The phosphorus used in fertilizers for the most part is derived from rock phosphate, which is becoming more scarce with time (here’s an article that discusses a few aspects of that whole thing as it pertains to global agriculture: Phosphate: A Critical Resource Misused and Now Running Low). There are other sources, notably from organic sources such as bonemeal and bat or bird guano, which can be combined with a growing media and which makes itself available to plants gradually and thus acts as a kind of organic slow-release fertilizer for plants.

As mentioned above, phosphorus is one of the macronutrients that are required for healthy plant growth (as opposed to the micronutrients, which, while also essential, are required by the plant in much smaller quantities). In most fertilizers, the three primary macronutrients are listed on the packaging as a ratio in the order of nitrogen, phosphorus and potassium, such 20-10-20 and 15-30-15. These may or many not have the additional macronutrients calcium, magnesium, and sulphur, as well as the fairly long list of micronutrients. In most fertilizers that you can buy ‘over the counter’, so to speak, the amount of phosporous will typically be equal to or greater than nitrogen or potassium. There are several reasons why this is ridiculous.

Plants do not use most of the phosphorus that is contained in these typical fertilizers. These high-phosphorus recipes have their origins in field crop production, where phosphorus behaves quite differently than in our soilless media, and where yields can be significantly affected by the availability of this nutrient. Producers of fertilizers for domestic use typically market high-phosphorus fertilizers as producers of better root growth and better blooming, when in fact the extra fertilizer is of no use whatsoever. They make quite a killing at it, too, I’m sure. It’s pretty wasteful, though, as it happens, and it seems that, at least in some cases (see below), lower phosphorus can produce better flowering and better quality crops in general.

Additionally, the fact that the extra phosphorus doesn’t leach away and remains present in the soil can have some negative effects: too much can inhibit the uptake of other negatively-charged elements such as iron and manganese. It also readily precipitates with other elements, forming insoluble compounds which are unavailable to plants, such as calcium and magnesium phosphates, particularly at higher pH levels.

But so how much phosphorus do plants actually use? Not very much! This paper provides a good look at the use of phosphorus by azalea plants, and indicates that the addition of phosphorus above a certain (low) threshold made no significant difference to the growth of the plants in the study: Nitrogen and Phosphorus Uptake Efficiency and Partitioning of Container-grown Azalea During Spring Growth. And here’s another paper that shows that lower phosphorus levels can actually produce better quality crops, with more flowers that held for longer time, as well as increased drought tolerance: Improving Bedding Plant Quality and Stress Resistance with Low Phosphorus.

So from these and other studies, we can determine that phosphorus seems not to promote better blooming, yet somehow these fertilizers can seem to be effective, hence their continued use. What is it about them that makes them work? The answer is in the number to the left: nitrogen. Many of the ‘bloom booster’-type fertilizers have either reduced nitrogen or increased phosphorus/potassium levels, and a reduced nitrogen to potassium ratio is one of the ways to shift plants more into reproductive mode, wherein they obviously produce more flowers at the expense of foliar growth. Balancing plants between vegetative and reproductive growth is the art of the commercial grower, and it is a fine art indeed, and worth examining to the amateur grower.

Recommendations for commercial crop production of most tropical plant species (which, to be fair, are mostly grown for their foliage) is for the use of a fertilizer with a 3-1-2 ratio, though even this seems a bit high: compare it, for example, to the MSU orchid fertilizer, which is 13-3-15, and which is a fantastic recipe, in our opinion. This article from the American Orchid Society discusses some of the reasoning behind the ratio they use, and how it works to create beautifully balanced plants that grow and bloom at an optimum: Without High Phosphorus A New Fertilizer Proves Itself with Orchids. It’s important to note that this fertilizer was not developed specifically for orchids, but is rather a well-suited mix for plants of any type, being built on sound principle and good science. For those in the business, or those who really go through the stuff, it would be fairly easy to reverse-engineer it from the guaranteed analysis on the label if you have access to the raw materials. (A hint if you don’t want 200 lbs of elemental fertilizer sitting around- hydroponics stores often sell smaller bags of potassium nitrate, etc., though for an inflated cost.) If anyone is interested in doing this and doesn’t know how, say so in the comments and we’ll see if I can’t help you sort through it.

I find it a little funny that even though the recommendations for production are to use a 3-1-2 ratio, I see professionals further down the line such as interior landscapers or garden centres using something like 20-20-20 (or even 10-52-10 for new transplants). Phosphorus is about four times more expensive than it was ten years ago, and I don’t presume the cost will be going down any time soon. Given the plants aren’t using it, why throw your money into the dirt, so to speak? Even local orchid societies are applying high-phosphorus fertilizers to their collections, despite vendors at their meetings carrying the MSU feed! Old habits die hard, I suppose.

I’m not recommending that anyone rush out, buy a reverse osmosis filter and start mixing up batches of MSU feed to start doing their houseplants (well, I sort of am, though it is expensive and maybe almost as wasteful as the extra phosphorus I’m bitching about here, due to the waste water that RO filters produce- your plants would love you for it, though, particularly those that struggle with the ever-present nasties like flouride [like, say, every Dracaena], and with high total dissolved solids in general [like some orchids and most carnivorous plants]). But it is worth considering when choosing or mixing your own fertilizers. There are a lot of ones that you can find on the market that are in and around the 3-1-2 ratio (particularly if you’re not looking at the major brands, which have got a good thing going with their ‘root-‘ and ‘bloom-boosters’), and you can give yourself a pat on the back for having used less of an increasingly scarce fertilizer. You may also save yourself some nutritional problems down the road. And if your plants aren’t blooming as well as you’d like, there are other avenues to experiment with besides lowering your nitrogen (though it will probably help), like lowering your night temperature a little (tricky out of season, unfortunately), giving the plant more light, or reducing somewhat the amount of water you give it, all of which are known to promote reproductive growth. Some plants won’t even set buds until some triggers are hit, like shortened day length or extended drought. Another reason to know what you’re growing, I guess.

A photo of the Atlantic Forest of Brazil, a view of which prompted Darwin's words to the right. Image source unknown; retrieved from Projeto Entre Serras.
A photo of the Atlantic Forest of Brazil, a view of which prompted Darwin's words to the right. Image source unknown; retrieved from Projeto Entre Serras.
The cradle of humankind: the plains of Africa. Image © Gossipguy; retrieved from Wikimedia
The cradle of humankind: the plains of Africa. Image © Gossipguy; retrieved from Wikimedia

`…that the naturalist`s journey will go on forever. That it is possible to spend a lifetime in a magellanic voyage around the trunk of a single tree. That as the exploration is pressed, it will engage more of the things close to the human heart and spirit. And if this much is true, it seems possible that the naturalist`s vision is only a specialized product of a biophilic instinct shared by all, that it can be elaborated to benefit more and more people. Humanity is exalted not because we are so far above other living creatures, but because knowing them well elevates the very concept of life.’

E.O. Wilson, from Biophilia                

You may have noticed that we reference and tag a word fairly often here at In Situ: biophilia. Biophilia as a concept was developed by the great Edward O. Wilson, biologist, ecologist and prize-winning author, who used it to describe humans’ innate need for affiliation with other living things. From the plants we have kept in our homes since at least the beginning of recorded history, to the out of work domestic animals we still keep around (there aren’t many professional mousers or herders among them these days, at least from an urban perspective- I’m sure there’s still work in the country), to the way we design our cities and parks, human beings have always surrounded ourselves with other organisms. Here’s another (admittedly long) quote by Wilson, who can put it all much more elegantly than I ever could:

‘I have suggested that the urge to affiliate with other forms of life is to some degree innate, hence deserves to be called biophilia. The evidence for the proposition is not strong in a formal scientific sense: the subject has not been studied enough in the scientific manner of hypothesis, deduction, and experimentation to let us be certain about it one way or the other. The biophilic tendency is nevertheless so clearly evinced in daily life and widely distributed as to deserve serious attention. It unfolds in the predictable fantasies and responses of individuals from early childhood onward. It cascades into repetitive patterns of culture across most or all societies, a consistency often noted in the literature of anthropology. These processes appear to be part of the programs of the brain. They are marked by the quickness and decisiveness with which we learn particular things about certain kinds of plants and animals. They are too consistent to be dismissed as the result of purely historical events working on a mental blank slate.’

E.O. Wilson, from Biophilia                

So while at the time the book Biophilia was published (1984), there had been no empirical study on the presence of an innate biophilic instinct shared by all of humanity. Since Wilson’s introduction of the hypothesis, many studies have been done that highlight the importance of proximity to nature and other living things to our mental health (see this literature review for a good discussion on some of the studies that have been done: Biophilia: Does Visual Contact with Nature Impact on Health and Well-Being?). Beyond all this, and at the risk of relying on intuition when so many of our human eccentricities are indeed counterintuitive, it just feels correct. At least to me (biased as I might be). Any client I’ve ever spoken with has always pleased with having plants around, and they often comment on how much better a place feels, which seems like mission accomplished and hypothesis confirmed to me.

But how did all this come about? Rooted in our history the habits may be, but the fact that humanity is itself rooted in the natural world is what has caused our deep-seated need to be surrounded by nature. We are the product of a particular habitat, and to this day we still find space in our urban centres for an approximation of it. Think of practically any city park you can imagine. Open grassy areas, with scattered copses of trees; sometimes a pond, fountain or the like. Maybe something somewhat reminiscent of this?

Our species came to be in just such a habitat, and we still seek these same landscapes for comfort, relaxation and meditation. We select our homes in similar ways: perched atop a hill, overlooking water, with a few trees (not too many) here and there describes some of the most sought-after property available (and indeed will often fetch a hefty price).

Turn now to the indoors, where people have been keeping plants for at least as long as we’ve been recording history. All ancient civilizations have depictions of potted plants indoors in the images they created, and sometimes went through great lengths to cultivate plants difficult to grow outside of their native environment (the Romans were building greenhouses even before glass was invented). It is safe to assume that many of these were functional from a medicinal or culinary standpoint, though the Chinese have cultivated ornamental plants indoors for at least three thousand years. Plant mania swept homes and offices in the 1970s, to an extent that has not yet been rivaled (though what those early pioneers of the interior landscape industry would have made of vertical gardening technology!). The interior landscaping industry was born in this era, and has persisted since.

Said industry has often toted the benefits of keeping plants indoors, primarily from a health and employee productivity standpoint (I went through some of the science that these claims are based on here), and some companies have begun to reference the biophilia concept as another selling feature. They are certainly right to do so, but I doubt that many who belong to these organizations have actually read and understood the ideas behind the concept, and are genuinely interested in fostering the sense of interest and wonder in the natural elements we surround ourselves with.

What In Situ is trying to do (and what we would like to encourage the rest of the industry to try to do) is to create more of those moments when nature really takes us in, where time falls away and we are free to explore with our senses the structure of a leaf, say, or the contrasting textures or colours of different plants growing together, to go on Wilson’s ‘magellanic voyage around the trunk of a single tree’. We wish to recreate the forest edge, viewed from our comfortable place amongst the figurative grasslands of our urban interiors, which draws us nearer, showing us glimmers of the mysteries held deeper within. We want to replicate indoors the richness and splendour that has captivated us as a species forever, has inspired countless works of art, and that still, in the lives we live primarily apart from it, holds a special place in our imagination.

‘Among the scenes which are deeply impressed on my mind, none exceed in sublimity the primeval forests undefaced by the hand of man; whether those of Brazil, where the powers of Life are predominant, or those of Tierra del Fuego, where Death and decay prevail. Both are temples filled with the varied productions of the God of Nature: — no one can stand in these solitudes unmoved, and not feel that there is more in man than the mere breath of his body.’

Charles Darwin, from Voyage of the Beagle          

By using new and interesting species, and using familiar species in interesting ways, we hope to satisfy the biophilic instinct by completing indoor environments with the engaging natural elements that have been a part of our species’ evolution since time immemorial. When used this way, plants can create a kind of biotic warmth that tempers the sterility of many modern interiors. I don’t advocate turning every indoor space into a jungle (…): rather, the contrast between our manmade constructions and these natural elements are what highlights their presence and what really makes them come to life. The studies I referred to above seem to indicate that having these elements in sight from any area of an indoor space is the optimal placement, and this is the model that many in the industry use when designing their interior landscapes. It`s sound to me, but I feel it’s only effective if the elements are actually visually captivating: this is why we try whenever possible to use plants that people are not usually familiar with, and that have very unique textures or colours, or some other interesting facet to their biology that creates real interest. We seek to foster a true biophilia, through which we can draw inspiration, comfort and knowledge, secure in the surrounds of our earthly cohabitants.

Tillandsia landbeckii, growing where little else will. Image © Eduardo Vergara; image retrieved from Flickr.
Tillandsia landbeckii, growing where little else will. Image © Eduardo Vergara; image retrieved from Flickr.
Closeup of a Tillandsia sp., showing trichomes. Image © Josef Špaček; retrieved from Botany.cz
Closeup of a Tillandsia sp., showing trichomes. Image © Josef Špaček; retrieved from Botany.cz
Tillandsia biflora in habitat. Image © Jean-Francois Brousseau; retrieved from Flickr
Tillandsia biflora in habitat. Image © Jean-Francois Brousseau; retrieved from Flickr
Tillandsia recurvata growing on power lines, Tamaulipas, Mexico. Image © 0+000; retrieved from Wikimedia Commons
Tillandsia recurvata growing on power lines, Tamaulipas, Mexico. Image © 0+000; retrieved from Wikimedia Commons

While I don’t wish to discourage anyone from keeping Tillandsia at home, I think that it is important for people to develop a greater understanding of these fascinating plants in order for them to have greater success in their cultivation; they are not as easy of care as most retailers would have you believe, and some species, despite being common in cultivation, are unsuitable (or at best, very challenging) to grow indoors.

The genus Tillandsia is made up of more than 600 species, which is about a fifth of all species in the Bromeliaceae, which includes other favourites such as pineapple. They are distributed, as are nearly all bromeliads, across North, Central and South America (there is one species of Pitcairnea which made it Africa somehow). There is a large variety of form across the genus, as different species have adapted to widely different habitats, from montane rainforests that are some of the wettest places on earth, to arid coastal deserts that receive a scant 3mm of rain annually, at best, and knowledge of where a species originates is of great use when determining how to care for it.

Cultivators of Tillandsia often lump species into two general categories: grey- and green-leaved varieties. This is a pretty good place to start, in terms of their care; the grey-leaved species are typically from more exposed, sunny habitats, and are evolved to make use of the sometimes very little water they receive in these environments, while green-leaved varieties are typically from more shaded, moister habitats. There are exceptions, of course, and so I reiterate that knowing where a species is from will be give you the best chance at success.

The grey colour is due to the leaves’ trichomes, which can perform quite a few functions in plants, but which in this case are designed to capture airborne moisture such as fog, as well as reflect sunlight (up to 45%, apparently). Species will have more or less of these depending on how water-deprived or exposed its habitat is.

The ones more often in cultivation are typically the grey-leaved varieties (though Tillandsia cyanea is definitely another big player, even if it’s typically sold potted along with all the force-flowered Guzmania and Vriesea bromeliads), and I’ll mention a few things about their different habitats below.

Dry Tropical Forest

Many species inhabit dry tropical forest which sees precipitation for only part of the year. Examples of species include T. brachycaulosT. caput-medusae, and T. xerographica. As epiphytes, these plants are found at different heights on host trees, where there is good air movement (which allows the plants to dry after rainfall) and varying amounts of sunlight depending on where in the tree a particular species is found (and indeed, different species seem to have different preferences for what part of the tree they occupy). These species, because of their requirement for good air movement, are not particularly suitable for most terrariums (despite what you’ve heard), though they do much better in higher humidity than is typically found indoors. A larger terrarium with air movement via a computer fan or the like (see here for some ideas on how to do this, with the understanding that your own endeavors with electricity in moist environments are obviously your own problem) would probably be best, and indeed that’s where I’m having the most success with plants from this type of habitat. Being hung outside under a tree through the summer months (at least here in Toronto) would probably treat them just fine as well.

A note on the seasonality of these habitats: these forests are marked by distinct dry seasons with little to no rain, during which time host trees may drop all their leaves, presumably exposing any harboured epiphytes to more direct sunlight. There doesn’t seem to be much written on coercing these plants to bloom, but in my experience an increase in light can often do the trick, and may well be the trigger for flowering that the plants use in nature.

There are also many Tillandsia species in cultivation which are from disturbingly arid habitats. These are the stiff, very grey-leaved species that are adapted to take what they can get, water-wise: T. tectorum, T. albida and T. edithae are a few examples of species. I say disturbingly arid because these can be some of the driest habitats on earth: the Atacama coastal desert of western South America, for example, has a few weather stations that have NEVER RECEIVED RAIN. Tillandsia species from the Atacama have evolved to take advantage of the coastal fog that rolls in from the ocean, allowing the plants to capture airborne moisture. Some xeric species inhabit high elevations in the Andes, and take advantage of the clouds that float through their habitats.

These species are much more tolerant of dry air, direct sunlight and restricted moisture, but the converse to this is that they need a lot of sun and also cannot be kept too moist. South-facing windows (or, optimally, a solarium or greenhouse) are probably best in the case of these plants, and they are definitely not suited for most terrariums.

A note here on watering Tillandsia: these plants use CAM (Crassulacean acid metabolism) photosynthesis, which is really neat and interesting and worth talking about at length, but which for our purposes here means that they open their stomata to absorb carbon dioxide at night rather than during the day as do most other plants. Wetting the plants before nightfall can inhibit this gas exchange and in effect suffocate the plants. The xeric plants, at least, receive moisture in their native habitat before dawn, allowing them to absorb carbon dioxide and then liquid water before the demands of the desert day begin. I don’t advocate waking up at 4:00 a.m. for any reason (though maniacal plant care is, in my opinion, a better reason than most), but watering your Tillandsia in the morning is probably best practice. And water them well: aside from the really effective water-catchers like T. tectorum, the oft-recommended misting with a spray bottle isn’t going to do much for the plant: give it a good soaking with a watering can or a quick dunk in a bucket.

Moist Habitats

Though not as common as the ones you find piled haphazardly in a basket at your local florist or garden centre (can you tell that gets on my nerves?), these are my personal favourites. Even T. cyanea, which is pretty boring as far as these go, foliage-wise, is an easy to grow species that does well in a pot. These species are, as far as I know, strictly epiphytic, and inhabit some of the wettest habitats on earth. The aforementioned T. cyanea, T. flabellata and T. biflora are three that can be found with a little digging (some more than others).

Conditions should be moist and humid, but with very good air movement, and lighting can be lower than for species from the previous two habitats I mentioned, so if you’ve been losing plants due to a combination of low light and excessive moisture, you might want to try one of these. T. cyanea is a tough plant, but T. biflora, in my experience, is not, and best results will be had in a greenhouse or large terrarium with good air circulation.

There are obviously gradients to these habitats I’ve mentioned here, and research into what species you have will give you the best idea of how to care for it. A little experimentation never hurts either (OK, sometimes it does), and you may find that some species are quite forgiving in cultivation. The lesson here is that, at least nine times out of ten, your local purveyor of Tillandsia hasn’t the slightest idea of how to keep them alive over the long term (you can even buy them in furniture stores now, apparently: I saw a bunch of mounted ones piled crudely on top of each other in a West Elm store here in town), so you should do your homework if you’d like to have success with this interesting group of plants.

Sporophyte fronds of what I`m presuming is Adiantum peruvianum, doing their thing in one of In Situ's vertical gardens. Image ©  In Situ Plants.
Sporophyte fronds of what I`m presuming is Adiantum peruvianum, doing their thing in one of In Situ's vertical gardens. Image © In Situ Plants.

Just a short one here, but I’m pleased to report that the little gametophytes I wrote about back in June have started to produce their first fronds, AKA sporophytes (being the part of the plant that eventually produces the spore which gifted us with the gametophytes in the first place). Again, I can only presume that these are Adiantum peruvianum, as this is the only fern species in this garden, but there are a lot of other ferns here at the lab (to say nothing of the effectiveness of travel by spore; these ferns really could be from anywhere), and so I’m still not 100%. (And there’s actually a terrarium in another room of the building that appears to be growing something similar, so the plot could still thicken here.)

They’re pretty cute, though, either way. As soon as we start to see more mature foliage on these plants I’ll update again with a more conclusive ID. The plants pictured here are way up at the top of the wall, and should produce a nice (albeit unplanned) cascading effect once they get going (again, presuming they’re even A. peruvianum).

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