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