My daughter has been studying the water cycle at school, so I decided it would be the perfect time to plant a couple of terrariums for our house. What is a terrarium? A terrarium is a container garden that is enclosed within glass or plastic, so that you create its own mini environment. Light and heat exposure result in evaporation and when the vapor hits the sides of the container, it condenses and heads back into the potting soil mix. If you have right moisture balance, your plants do not need watering and will need little care until they grow too large for the space and will either need to be pruned or replaced.
We started our project with a trip to a local garden store in search of small plants that would fit into our chosen containers (a plastic teddy bear that once held animal crackers and an old rice container). This actually turned out to be the biggest challenge in the process. Most of the indoor plants we found were either too large or vigorous vines. Finally we spotted two small indoor plants that would work, a pink nerve plant and a small peace lily. Even though they were small, both needed a little pruning to fit into the containers. (*A tip from past disasters, avoid plants that appear to have any type of fungal or bacterial problems. The humid environment of a terrarium will foster the growth of any existing disease problems and the terrarium will be short-lived.)
Once home, we gathered the rest of the supplies (the cleaned containers, pea gravel, and potting soil mix) and headed out to our back porch. If you are still knee deep in snow, you can also do this as an indoor gardening activity. On the messiness scale of 1 to 10, it is probably only about a 4, but you may want to lay down some newspaper underneath your work surface to help catch stray potting soil.
The first step was to fill the bottom of the container with pea gravel. Some folks will then put a layer of filtering charcoal on top of the gravel. I usually don’t have it on hand and don’t worry about it. As long as you maintain proper moisture levels, you don’t need it. Next, we carefully moistened the soil. The potting soil mix should feel like a wet sponge – if you can squeeze water out of it, then it is too wet. Then we scooped the soil into the container (we lost my son at this point, he was quite upset about getting his rocks dirty, sigh) and added the plants. Planting took a bit of maneuvering since the openings were pretty small, but that made it a good activity for small hands. After we planted, we used a paper towel to remove soil that ended up stuck along the sides. Finally we put the top on and placed in a sunny window.
The first few weeks, we will watch it to make sure the moisture levels are correct. If the sides of the container are drenched when in full sun, it means we have too much water, which can be solved by leaving the lid off for a while. My daughter has also informed me we need to find a little plastic frog to live in our terrarium… that might end up being a bigger challenge than finding the plants.
Need guidance and inspiration? Check out Building a Terrarium.
Want ideas to use terrariums as a teaching tool?
Download: The Water Cycle: Exploring Terrariums Lesson!