If you can’t join us for one of our signature terrarium workshops, try your own at home with our basic guide.
Creating Your Terrarium
For your new terrarium to succeed, it is extremely important that it is properly installed. Selecting the appropriate plants is critical. Plants need to be compact and slow growing, as well as compatible to the same conditions as companion plants. Additional materials, such as rocks, or driftwood should be thoroughly rinsed with hot water to kill any organisms which may be present.
Your planting foundation will consist of four layers:
The bottom layer is for drainage and consists of pea gravel, pebbles, or very coarse sand. Proper drainage is essential to ensure that the soil does not become over-saturated, which may lead to root rot and the death of your plants. Depending on the size of your container, you will want to spread at least 1” of drainage material evenly across the entire bottom of your terrarium. For large containers, up to 3” of material may be used.
On top of the drainage layer, you will spread a thin layer of activated charcoal (aquarium filter charcoal). This layer will help clean the air of the fumes caused when the organic materials begin to decompose. The third layer is a thin cover of sphagnum moss, spread over the first two layers. The purpose of this is to prevent the soil from sifting down into the drainage layer, which would render it useless.
The final layer is soil. All purpose houseplant potting soil is fine. Do not add fertilizer to the potting mix as it already has enough nutrients to last a long time. Over-fertilizing will cause the plants to grow out of their surroundings too quickly.
While the bottom layers are uniformly laid, the terrarium will seem more realistic if you add depth and contour to your landscape with different levels of soil. You can create terraces, valleys, and hills. Use your own special pieces of wood or stone as landscape accents.
Planting Your Terrarium
While still in their pots, set the plants around the inside of the terrarium. Adjust the soil level to create hills or valleys, move your accent pieces to different locations within the landscape. Step back a foot or two and see if your arrangement has the desired effect. If not, do a little more rearranging, and check it again. When you have decided that you have created the right scene, you are ready to do your planting.
No special tools are necessary, unless you are using a narrow mouthed container. You can use a small shovel or kitchen spoon or fork. Remove the plant from its pot and place it into the pre-dug hole. Unless your plant is root bound, there is no need to loosen the roots. Firm the soil gently around the roots of the plant. After planting, the soil should be lightly moistened. The lid should then be placed on your terrarium. Check it frequently for the appearance of condensation on the glass. If large water drops appear on the glass, the container should be left open for awhile, until any excess moisture evaporates. In some cases, it may be necessary to keep the lid slightly opened to allow for fresh air circulation.
However a balanced terrarium should have a certain amount of moisture on the glass.
A completely enclosed terrarium requires little or no watering. If it is an open terrarium, you may have to water once a week or on a monthly basis. The addition of water only becomes necessary if no condensation accumulates on the glass. When water is needed, it should be added a small amount at a time, since there is no place for the surplus water to run off. Recheck the next day, and if no condensation has appeared, more water may be added. Over watering increases the risk of fungus or mold.
Generally, terrariums should not need fertilizing, but if plants appear malnourished, you may add a very weak (1/4 strength) of all purpose plant food.
Occasionally, it may be necessary to replace a dead plant. Diseased plants should be removed immediately. Although confined plants tend to grow slowly, any plant that has outgrown its environment should be replaced.