On Biophilia and the Value of Interior Landscaping

`...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 many 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?

The cradle of humankind: the plains of Africa. Image © Gossipguy; retrieved from Wikimedia

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 the forest. 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.

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.

‘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. 

Some Notes on the Natural Habitat of Tillandsia spp., and Inferences Therefrom on their Care in the Interior Environment

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. 

Closeup of a Tillandsia sp., showing trichomes. 

Image © Josef Špaček; retrieved from Botany.cz

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. brachycaulos, T. 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.

Tillandsia landbeckii, growing where little else will.

Image © Eduardo Vergara; image retrieved from Flickr.

Xeric (dry) habitats

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.

Tillandsia biflora in habitat. 

Image © Jean-Francois Brousseau; retrieved from Flickr

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.

Thematism in the Interior Landscape

“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

One of In Situ’s primary goals as a company is to increase interest in plants in order to reconnect people to the natural world. We believe strongly in the hypothesis of biophilia, first conceived by the venerable E.O Wilson; the human need to commune with other living things. We feel as though this is why people have always kept plants indoors, and that now more than ever it is important to continue the relationship.

We use several strategies in order to further this goal of increasing interest in plants: making use of the wide variety of less-often used species is a good example, as the visual impact is immediate and apparent. Beyond plants’ appearances, however, lies the really fascinating stuff, and this is what we like to bring to light in our designs.

Cyclosephala colasi on a Philodendron inflorescence. 

Photo © Marc Gibernau/Denis Barabé; retrieved from 

the International Aroid Sciety website.

Even the most commonplace species can hold fascinating features when they are brought into context. For instance, the humble Philodendron, long a staple of interior landscapers, has a unique aspect to its physiology. The inflorescences (flowers) of many species are thermogenetic: they produce heat. And quite a lot of it, as well: some species’ inflorescences can rise 10°C above ambient temperature! This interesting adaptation serves to volatize aromatic compounds that attract pollinators, of which beetles are usually the primary ones. See here to read more about thermogenesis in plants.

The above is just one example of the countless facets through which one can look at plants. There are many themes which we have explored; below are but a few.

Biotopes

Plants' natural habitats are, particularly in the case of the tropics, richly populated communities of species, with many growing closely around (or on, or in) each other. These ecological landscapes are referred to as biotopes, and these are interesting themes to explore, as they offer us a (somewhat stylized and selective) glimpse into where these species are from. To actually see these habitats in person is incredible, and we want to share this with our clients. Using solely plants from a particular region can highlight, for example, an area under grave threat of deforestation, highlighting the need for conservation.

Natural Variation within Species
The world of plants is one of incredible diversity, and even within species, an incredible amount of variation can be seen (see this post for more thoughts on this). Another perspective on this variation is convergent evolution, in which completely unrelated species evolve similar forms to solve the same problem. For example, many of the Euphorbia species from Africa and Madagascar often look for all the world like cacti (which are only present in the Americas), but are from a completely different family. These disparate species have come upon similar means of water storage (water-holding stems) and self defense (spines) that allow them to exist in some of the harshest habitats on earth.

Epiphytes
The epiphytes include many of our favourite plants, and many species which people are used to seeing in pots actually spend their entire lives without ever sinking their roots in soil. Orchids and Tillandsia bromeliads (the now very popular ‘air plants’) are some of the more commonly recognized ones, but the vast majority of tropical plant species are in fact epiphytic. Some of the more common epiphytes available are lipstick vines and goldfish plants (Aeschynanthus spp. and Columnea spp., respectively), begonias, many aroids such as Anthurium and Philodendron, and many ferns. Using exclusively epiphytes together allows us to see the richness of these plant communities living far from the forest floor.

The Carboniferous garden: Afrocarpus gracilior, Zamia furfuracea, Asplenium
nidus, Microsorum pustulatum and Psilotum nudum. Image © In Situ Plants.

The planting pictured here is a good example of how we are able to execute the types of themes we explore, and also of how we, too, learn something new about plants nearly every day. We really wanted to make use of a particular tree, Afrocarpus gracilior, (also known as the Weeping Podocarpus), as the texture of the foliage and its dense, shaggy habit makes a really dramatic statement. It is also unique in that it is a tropical conifer, distantly related to our familiar spruce and pine. This group of plants, the gymnosperms, does not produce flowers, though it does produce seed, and arose during the Carboniferous period of Earth`s history, some 300 million years ago. It is this latter fact that we decided to explore for this planting.

The Carboniferous is so named due to the fact that this is when the great forests that were destined to eventually be swallowed by the ocean and preserved in the familiar form of coal were at their peak. It would have been a different landscape than the one we are used to today, for flowering plants had not yet evolved, and more simple plants dominated the prehistoric flora. Among these were the simple vascular plants which reproduce via spore such as ferns, tree ferns, and allied families, and the first seed-producing plants, of which A. gracilior is one.

Another primitive plant which produces seed but no flowers is Zamia furfuracea, also known as the cardboard palm. This is a cycad, related to the more commonly seen Cycas revoluta or sago palm. This plant was definitely a candidate for this installation, and its coarse texture and olive colour contrasted perfectly with our Podocarpus.

We had to represent the family of ferns in this planting (being one of the dominant flora of the Carboniferous), and chose two that highlighted the extraordinary diversity of form seen in these plants. Asplenium nidus, the birdsnest fern, with its rosette form of bright green, undivided fronds, is an epiphytic fern that grows on trees in Australasia.  Microsorum pustulatum, the kangaroo fern, takes another approach to its growth: it creeps along on a hairy rhizome, from which emerge deep green, incised fronds which are more classically ‘fern-like’ than A. nidus.

One final plant was used in this installation: Psilotum nudum, the whisk fern. This species was chosen more for its story than for its form, which is nevertheless an attractive bunch of semi-erect stems, from which are produced spherical synangia, which contain the spore the plant uses to reproduce. The species has no leaves, no roots, and only half a vascular system, and is very primitive indeed in its physiology, and was a must-have for this planting. What we discovered in our research, however, was that there is some evidence that suggests that P. nudum may actually be descended from more complex fern species, and that it may have reverted for some reason to this very simple form. Perhaps we will never know for sure, but P. nudum is definitely a great representative for other similar species which were prevalent during the Carboniferous.

These themes tend not to be immediately apparent to the casual observer, of course, unless the plants are unified by a physical characteristic, and so the obvious question is why bother? We are able (and would be more than happy) to produce educational signage for anyone who wishes to show off the subtleties of their interior landscape, but we feel that with this much intent in our work, there will be a mood created which is tangible, and which adds depth and value to our landscapes. We hope to draw the viewer into our world and experience plants on a new level, and to connect them with a world most urban residents would never encounter otherwise.

Plants that Shine: Iridescence in the Indoor Garden

Selaginella uncinata.
Image © 天問 小窩; retrieved from Wikipedia

Iridescent plants are a welcome addition to the interior landscape: who wouldn't want a shimmering blue plant in their presence? There are several species (most only marginally available in cultivation) that exhibit this exciting type of colouration; Selaginella uncinata is perhaps the most available, under the name peacock spike moss. It can sometimes be found at garden centres and the like, and is produced by Exotic Angel Plants, amongst others.

I recently read an interesting article in The Scientist magazine on natural iridescence which explained something fascinating: iridescence is not caused by a pigment or a dye, but a structural property of the leaf (or wing, or feather, or whatever). Textures of the tissue surface are covered in ridges, bumps and dimples that refract the light in a way that appears to us as a metallic sheen. This adaptation is thought to have arisen during the Cambrian Explosion, as creatures were developing the first primitive eyes able to sense light, dark and contrast.

Elaphoglossum metallicum, another iridescent plant.
Image © In Situ Plants

In cultivation, plants known for iridescence such as S. uncinata can show more or less of this colouration under different cultural conditions: I find that the best conditions for S. uncinata are moist, shady and humid (my default conditions for the genus). In bright light, this plant will blush pinkish-red, which can create a spectacular effect coupled with the iridescent blue, though it is a fine line to achieve both and maintain both colours. Apparently the ratio of red to far-red light makes a large difference in the production of iridescence, at least in the related species Selaginella willdenowii., though that`s somewhat outside the realm of the casual grower to play around with.

But perhaps the most intriguing aspect of this whole thing is the why: what evolutionary benefit do plants gain from this colouration?  A paper published in the Journal of the Royal Society suggests two possible advantages: the iridescence may act as a deterrent to herbivores, as the (seemingly) constantly changing shape would not allow herbivorous insects, for example, to develop a search image (a familiar shape which the insect recognizes as a food source: search images abound, in our own minds as well as those of insects). The other possible advantage is that the iridescence (which is primarily seen in shade-dwelling plants, as I mentioned earlier) can prevent damage from exposure to too much light, say from a newly created hole in the canopy overhead that permits direct sunlight to reach the forest floor.

Whatever the reason, these plants hold a special fascination, and they are beautiful to behold. With a little care, these can make incredible additions to anyone’s indoor garden (and outdoor garden, if you are fortunate to live in a place with mild enough winters to get away with it).

On Natural Variation and its Place in Interior Landscaping

The world of plants is one of staggering variety: to date there are around 400,000 species known to science, with many more waiting to be discovered. An interesting facet to this variety is the fact that there can be incredible diversity within species themselves, such that different individuals of the same species growing side by side might not be immediately recognizable as being at all related.

Philodendron hederaceum and Philodendron 'Brazil',
a variety of the species, growing  together in a
vertical garden. Image © In Situ Plants.

Oftentimes, a variety will supercede the parent species in popularity, perhaps because it performs better in cultivation or has a more interesting appearance, and becomes used more often than the 'original' species. (Note that I am not discussing man-made hybrids or cultivars here- that is a subject for another time.)  A perfect example is Dracaena fragrans 'Massangeana', which sports a pale green stripe down the center of its leaves not present in the typical D. fragrans. One doesn't even really see the boring old D. fragrans anymore, so popular has its variegated variety become. 

But would the effect of 'Massangeana' not be greater if it were a single specimen amongst several of the regular D. fragrans? After all, that's how one would find such a variety in nature: they would stand out like a sore thumb, and perhaps even give taxonomists a run around thinking it might be a different species. I think it would, and so that's what I do with these types of plants.

I believe that, rather than leaving these varieties to stand alone as representatives of their species, they should be incorporated and used (sparingly) with their parent species to highlight and exemplify the fact of their origins, and to allow people a glimpse at the near endless variety of the plant kingdom.

Ferns from Scratch, and Some Interesting Facts about their Method of Reproduction

Closeup of Adiantum peruvianum showing sori. 

Image © In Situ Plants.

I recently noticed, to my great excitement, that some fern spore had germinated in one of our vertical gardens. In this case the species in Adiantum peruvianum, the Peruvian maidenhair fern, a delightful species with unusually large pinnules (leaflets), and which eventually grows fronds a metre long in ideal conditions. When this species was planted, the fertile fronds were already showing the sori (clumps of sporangia which produce the spore) along the margins of the pinnules, and I had hoped (and had really thought it was against the odds) that some of the spore would in fact do its thing in the garden. Lo and behold, here we are.

You may know that the ferns are a fairly primitive group of plants that were on earth a million years before the dinosaurs, having only a rudimentary vascular system and never having developed flowers or seeds. In the right conditions, propagation by spore seems to be an extremely effective means of reproduction, provided a few basic needs are met.

In flowering plants, a seed produces a plant which grows to maturity, produces male, female or dioecious (male and female) flowers, pollinates and/or is pollinated, and the pollinated flower then produces seed to complete the cycle. In ferns and other spore-producing plants (mosses, liverworts and tree ferns), spore germinates and produces a gametophyte consisting of a single simple leaf called a prothallis. It is the gametophytes which do the reproducing in these plants: the male organs of the gametophytes release sperm, which, dependent upon the presence of a film of water on the surface of the growing area (certainly one of the reasons why these plants are usually restricted to moist, humid environments), travels between gametophytes and fertilizes the female organs. At this point a new plant is produced which is immediately more

A. peruvianum gametophytes, in a somewhat

underwhelming photo. Image © In Situ Plants.

recognizable as a fern, and which will reach maturity and itself produce spore to complete the cycle. Colonies of gametophytes can apparently continue to produce ferns for some time, so in cultivation plantlets can be removed and the colony left to continue to reproduce, which is a pretty good deal. 

 

With my little A. peruvianums, the first part of the cycle is complete (although perhaps it's difficult to call a part of any cycle the first part). What remains to be seen is whether germination can be achieved: the outermost layer of the garden material does not have the constant film of water that the habitat of A. peruvianum does, but I am attempting to keep the area as moist as possible in an effort to assist germination. Here's hoping for a favourable outcome; the little gametophytes certainly do add an interesting element to the garden, though, at any rate.

The Space Between: Why the Immediate Lushness Effect Works Against Itself

Philodendron hederaceum and P. 'Brazil',
growing as nature intended.
Image © In Situ Plants.

We love plants for who they are. We like to see them grow as they have evolved to do, and vertical gardens provide a perfect medium for many plants to do so. The epiphytes (those plants that grow upon trees and other plants) and hemi-epiphytes (those that start life on the ground and then grow up towards the canopy) in particular are very at home in this environment, provided a few basic needs are met.

Without reaching too far into the reasons why many vertical gardening systems are designed to be densely planted from the outset (it seems to have been a natural progression for the industry to provide an instantaneously lush and full garden instead of one which required time to reach its intended glory), we can easily see the effects on the plants themselves. Commonly used plants which typically climb in their natural habitat are perfect examples of this: how often do we see a pothos or Philodendron climbing up a wall instead of cascading down? The weeping effect that the latter creates is admittedly pleasing (though there are plants which naturally possess this type of growth), but I believe that to create a truly spectacular and natural effect the best thing is to allow the plant to grow naturally; that is, up. And to do this, the plant needs space.

Many vertical garden systems are composed of cells, many filled with growing media, and some merely holding potted plants. These systems are fantastic if frequent replacement of plants is necessary, but this type of growing environment does not emulate a natural one. Other systems employ an undivided planting area, where roots are free to grow where they will. In these systems, if a plant is provided sufficient space, it will begin to grow upward, affixing itself to the growing surface with its aerial roots, tendrils, suckers or rhizoids, depending on the species in question. Once growth begins in this fashion it progresses rapidly, and something even more fascinating begins to happen: the plants' new leaves begin to grow larger than the last! Simply as a result of being able to grow as it has evolved to do, the plant performs better and produces a nicer specimen than one constrained in a planter.

Immature Monstera dubia. 

Image © Anna Haigh; retrieved from CATE Araceae

This effect becomes more dramatic still in the case of some hemi-/epiphytic species because they possess a juvenile and adult form. Monstera dubia is a splendid example: the juvenile form of the plant grows with its silver-brushed leaves tightly appressed to the growing surface, but when it reaches maturity it suddenly abandons this growth pattern to produce large green leaves which take full advantage of the higher light in the forest canopy. It uses this extra energy to finally, after its long climb, produce flowers and ultimately reproduce. Incredible!

Many designers of vertical gardening systems seem to have lost their way; in what other horticultural discipline has a garden ever been designed to be instantaneously lush and full (or crowded, for that matter)? Certainly not in most traditional landscaping, and not even in most interior landscaping situations. It is a pity that now many people showing an interest in these gardens are expecting such fullness at the outset, for it is truly at the expense of the true potential of the vertical garden and the species therein.