A terrarium is a good way to grow small plants in a confined space—but it can also be much more. This is another bit that was cut from Australian Backyard Naturalist, mainly on account of space. So here it is, for free!
For a good terrarium, you need an old fish tank which does not leak, gravel (you can buy it by the bag in aquarium shops, and tthe next entry will show you how to use what is left-over), washed coarse sand, a few stones and pebbles and some plants that do well in moist conditions.
If you can get one, use a daylight electric light (you can get them at aquarium shops) or place the tank on a window sill near (but not in) sunlight. If you can't arrange that, choose shade plants.
Put a sloping layer of gravel in the tank, 2 cm deep at one end, with no gravel in the last 10 cm: this is where there will be a water pool. Then add sand over the gravel to make a 10° or 15° slope along the length of the tank (you can leave out the gravel, if the sand is coarse-grained). Once again, leave one end free for a pool. Pack the sand down as you add it and water it gently: the excess water will run down and pool at the low end. You can grow duckweed and algae on and in the water.
Then plant mosses, bryophytes, Selaginella (club moss), weedy things and small ferns, up and down the slope, and maintain the water level. Collect small samples of moss when you are out and about, dividing each piece into three parts to place on the slope at different levels so they can thrive in the best environment. Use small plants: I like to add the odd small fern and small weedy-looking shade plants. Violets do well.
Add a few river pebbles as part of the dry surface to provide more niches. A piece of granite is good on the water's edge, because mosses and algae can grow up it. After that, just keep adding bits and pieces and ripping out any plant that gets out of control.
You can water the system by leaving an upside down soft drink bottle sitting on a rock at the lower end. This keeps the water level constant over a long period of time, which is very useful during holidays. If you will be away for a long time, you will probably want to cover the tank in cling wrap as well. From my tests, a one-litre bottle is good for a fortnight in hot weather with a flywire cover.
Occasionally, water gently up and down the slope with a watering can to maintain a bit of variety, and to help the mosses and ferns which need free water to breed. You can also spray the surface with a wash bottle, splashing water through the flywire to make "rain".
My terrarium used to double as a guest house and recovery room for semi-drowned frogs from our pool, so it was covered in flywire to keep the humidity down, and there was a small hole in the flywire at one end. The upper half of a funnel cut from a soft-drink bottle went through this hole. I would put a piece of fly wire and leaf litter in this funnel. As it dried, the smaller animals just migrated down and fell into the tank.
If the arthropod population blew out and there were no frogs in residence, I would send in a few spiders to clean up. The best spider is the household "Daddy Long Legs" spider. I tried a centipede for a while, but it did not do much. It survived, so if you want to keep centipedes, there's a hint for you.
The flywire stayed on under the weight of the funnel, as I always shape my flywire covers like the lid of a shoe box and then "stitch" them into that form with a stapler or copper wire—you just lift the lid off when you want to garden, or add some new bits of moss, fern or whatever. The flywire also keeps the spiders in and the mossies out.
I keep another source for water for the pool in the terrarium tank. I always have a few two litre apple juice bottles with a pinch of commercial "plant food", inorganic fertiliser, in each of them, with duck weed, algae and the occasional dead leaf from a nearby creek to add more life.
These bottles are kept about two-thirds full, allowing the water to "breathe" through a larger area and I keep a spare bottle with just tap water in it, water that is "ageing". Time taken each week? About two minutes, plus the messing-around time when I bring samples home, maybe five minutes a week in all. But I spend much longer just looking . . .
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This blog covers quite a few different things, so I tag each post. I also blog about history, and I am currently writing a series of books called Not your usual... and the first two have been accepted by Five Mile Press, The offcuts appear here with the tag Not Your Usual... . For a taste of Australian tall tales, try the tags Speewah or Crooked Mick. For a miscellany of oddities, try the tag temporary obsessions. And language us covered under the tags Descants and Curiosities, while stuff about small life is under Wee beasties.