Information to give for a good plant recommendation

[schmiggle]

I think there have been a few times now where either someone has posted to this forum asking for a good easy plant for a terrarium, or has asked me personally for help, but has given absolutely no information on what kind of conditions they were talking about. While I would love to help, I basically can't make suggestions without some kind of information on the terrarium. Plants are just as alive as animals, and often have equally complex needs, so there are certain things that I, and I imagine anybody, need in order to make any kind of informed suggestion.

That being said, here are, I think, the main things one needs to know about a terrarium to suggest a plant:

• What intensity of lighting do you have/are willing to buy, and ideally in what part of the spectrum? This would ideally be given either in footcandles, or equivallently in lumens with distance from the plants. This is probably the single most important issue in a terrarium: most arachnids have poor eyesight and/or are nocturnal, so they don't need very much light, but plants almost all need higher intensity lighting or they will starve. As a general guideline, I think most plants need at least 250 footcandles to do well, although some can get by with as little as 10.
• What kind of soil are you using in the terrarium, and are you going to put your plants in a pot? Soil depth in a terrarium is often too shallow for most plants, so that is one of the places where knowing about soil, and maybe using a pot, is helpful. This is even true for some smaller species, especially desert ones: Lophophora cactus, for example, may grow only a couple of inches high above ground, but can have a foot-long, tuber-like root. In addition, most terrarium substrates are made to be purposefully nutrient-poor in order to keep them from degrading over time. This is detrimental to a plant, which absorbs all of its chemical nutrients from the soil (carnivorous plants and, to a lesser extent, epiphytes being exceptions). This is another place where a pot helps: keeping a plant in a pot means that it can get its ideal soil while the animal its with can get its own ideal substrate.
• In a similar vein, how moist will you be keeping the soil in your terrarium? Animals, as a group, have a wide range of preferred soil moistures, from bone-dry to waterlogged (though the latter is quite uncommon), and plants are the same. This is another reason to use a pot--the moisture in the pot, especially a glazed clay or plastic pot, can be significantly different from the surrounding substrate (unglazed clay is porous, and so loses water in dessicating surroundings).
• What kind of humidity will the terrarium have? A lot of plants like high humidity, especially since some (like pothos) can absorb humidity from the air and thus need to be watered less often. Pothos, orchids, and many other houseplants all love high humidity (they come from equatorial rainforests, after all), and would do quite poorly in a desert terrarium. The reverse, luckily, is often a non-issue: cactuses and succulents do fine at high humidty. However, humidity is linked directly to soil moisture, and cactuses and succulents will get root rot if their soil is too wet.
• What kind of temperatures will the terrarium have? Many plants have a wide range of acceptable temperatures, or equivalently are quite happy at the temperatures the animals like. This is thus often a non-issue. However, it is worth mentioning, just in case one decides to, say, keep some kind of highland plant, which might need a temperature drop at night.
• How big, and especially tall, is your terrarium? Many of the easiest and most common plants, especially low-light ones--zz plant, cast iron plant, chinese evergreen--get quite big (just look up pictures to see what I mean). Plants don't need anything like as much space as an animal of equivalent size, but they do need enough room to fit into.

I can't think of anything else right now, but if anybody has other suggestions, just mention them in the comments so that this list is as comprehensive as possible.

Basically, in short, if you want a plant suggestion for an animal terrarium, tell us: light intensity, soil depth and type, moisture, humidity, temps, and terrarium size. Mostly all the same information as an animal, except maybe the lighting. And just like animals, many plants can thrive in a home environment, as long as they are given the respect and care that they need.

 

[The Snark]

Excellent post, @schmiggle
Not a suggestion but rather a heads up.
While it is quite possible to grow plant X in environment Y, terrarium plants are invariably in a synthetic environment. There is no established self sustaining ecosystem. Thus, an ecosystem often becomes your worst enemy in maintaining the terrarium. The micro-organisms, the detritus layer, the symbionts, the cobionts and undesireable plants and animals are all components of virtually every ecosystem.

These factors should always be taken into account when designing and planting out the terrarium. There will always be invasives, problematic somethings that came along for the ride. Expecting them and doing some research in how to live with them or control them is always in order. From odd or foul odors to sudden inexplicable die offs, take as much of the web of life into account as you can.