The few needs of terrariums allow them to be all but forgotten, then noticed in some idle instant between the bustle of tasks that occupy our lives, giving sudden delight. Here is a unique opportunity to set a little world in motion and then leave it be.
Terrariums are one of those pleasant distractions that remind us life isn’t about meeting goals. Every terrarium is a perpetual experiment. Plants react in surprising ways to the humid environment. Roots grow into the air and along the glass as well as in the soil. Flowers grow and hang on their stalks, untouched by bee or gust of breeze.
Terrariums remind us to wonder and make us forget ourselves for an instant. They are similar to bonsai in their capacity to create a true to scale world, but unlike bonsai, they don’t take much care.
One of the things I love most about terrariums is how simple they are. All you need is a glass container with an airtight or close to airtight lid, growing medium, something to grow, and some water.
A terrarium can be as basic as a single piece of moss in a glass jar, or it can be as elaborate as a hundred gallon aquarium with artificial grow lighting. You may love the challenge of working in tiny containers or vessels with narrow entries or you might prefer a cake platter or wide mouth design that allows you full access to the plants inside.
Gravel, Sand, and Dirt
My terrariums contain three ingredients: fine gravel or sand, dirt, and moss and plants. I can add as much gravel or sand as I want in decorative patterns, or so thin a layer that it vanishes under the moss.
I keep the soil to a minimum, just enough to cover the root balls of plants. I cover any exposed soil with moss, gravel, or other decorations. Exposed soil, wood, or organic matter has a tendency to grow mold.
I use water from my pond to wet the terrarium when I make it, which is all the fertilizer it will need until it wants water again, which won’t be for months. You can use any dilute liquid fertilizer, but don’t overdo it.
Since you aren’t using much soil, the plants need the nutrients in liquid fertilizer to continue to thrive, but you don’t want plants to grow too quickly, and nutrients won’t be washed out in the contained environment.
An organic option like Seaweed Fertilizer is a good choice, as it is unlikely to be overconcentrated. Seaweed fertilizer contains lots of the trace elements that the container plants in your terrarium will use up.
Another option is a good all-purpose plant food in a mini size. This is convenient since you won’t need more than a drop or two each time you water.
Choose plants that favor bright indirect light and humid conditions. Most small jungle plants work well. If you don’t mind turning the terrarium and trimming the plants frequently (you can plant the trimmings right back in the soil, or start another terrarium) there are many options.
Easy flowering plants include: begonias, impatiens and peace lilies; while the gorgeous leaves of polka dot plants and coleus can spice up the terrarium between blooms.
If you would rather have a carefree terrarium that looks good all the time, choose specimens that tend to grow slowly and stay small. African violets and miniature orchids are good options, as are delicate species of ferns like the maidenhair fern.
Zamioculcas, ivy, ficus, and azalea have all done well in my terrariums without taking over. Even if you use mosses alone, you are likely to get some volunteer ferns like the maidenhair fern.
There are lots of mosses that can be used successfully in terrariums, whether you find them on wood, stone, or soil. Try to take as much of the base material as possible when you collect.
Terrariums thrive in bright indirect light all day. Direct light can be dangerous, causing leaf burn and overheating the glass environment, so bright indirect light is best.
Watch young leaves and the tips of the mosses and move into less light if you see yellowing or burning.
If you would rather have complete control of your little world, use a full spectrum grow light, and carefully monitor how close to the light the terrarium is to avoid burning. Generally, two to three feet is about right.
If plants appear dry, add a mist of water every day until they seem healthy. Er on the side of dry. More plants die of too much moisture than too little in a terrarium. Add water slowly and wait for a response, rather than dousing the environment with too much water. If too much water is added, you can leave the lid open for a couple of hours at a time to allow for evaporation.
Don’t worry about doing much to maintain your terrarium. If the water and light levels are right, you won’t have to tamper with your little world for months.
When you finally open your terrarium to trim plants or perhaps wipe the glass if it becomes dirty with snail tracks, it should smell like rich dirt after a rain. If you see any signs of mold or rot, remove them and consider adjusting light or water levels.
I hope you enjoy making terrariums as much as I do. I have found few hobbies that combine my love of art and plants as affordably and easily, or that offer so much magic for the effort. Don’t hesitate to contact me with any questions at all! I absolutely love talking about terrariums.