If you want to create an intriguing display, encase a small garden in a glass container to form a terrarium. Different from an outdoor garden, a terrarium provides a warm and humid atmosphere with everything your plants need and with very little maintenance, provided you use the correct type of soil. Soil, however, is only part of the equation. Layering the soil base to provide drainage, adequate moisture and an odor-free environment produces the best results. Here’s a short guide on what types of soil to use in a terrarium.
If your terrarium is on the small side, you may want to increase the amount of sand and decrease the amount of soil. Add distilled water to make damp but it is easier to transfer to terrarium when it is dry. Remember – you can always add more water to your final terrarium but it is difficult to remove!
Here are the best type of soil to use for terrarium:
Packaged or bagged soil specifically formulated for terrariums often can be purchased at home-and-garden centers as well as pet stores. It is sold for terrarium like reptile habitats. Standard packaged potting soil also can be used for a plant terrarium. Regardless of where you get soil, it needs to be clean and high in organic matter.
It often contains all of the ingredients needed for healthy, thriving terrarium plants.
It is already sterilized, making it ready to use without further preparation.
Potting soil formulated for terrariums often contains one part sand, one part peat moss and one part sterilized garden soil with added amendments. The amendments may include sphagnum peat moss, which is naturally resistant to bacteria, vermiculite, which helps with water retention, and perlite, a natural, volcanic amendment added to increase air circulation around delicate root systems of plants.
Assembly of the Soil Base
Most containers used for terrarium gardening have no drainage holes; stagnant moisture can become quite malodorous if you don’t provide a way to drain water away from the soil base. Keep your terrarium smelling fresh and clean by lining the bottom of the container with a 1-inch layer of potting glass or stones to allow water drainage and to allow that water to evaporate. A 1/2-inch layer of activated charcoal should be placed on top of the pebbles. Add on top of the activated charcoal a thin layer of fresh clump moss.
Terrarium plants are not meant to be vigorous growers. So use fertilizer sparingly and infrequently. Otherwise, the level of maintenance the terrarium requires will increase substantially. Before putting potting soil in a terrarium, an option is to mix it with fertilizer. One level teaspoon of 5-10-5 fertilizer can be added to one 6-inch potful of soil mixture. If you use potting soil without fertilizer and your plants do not grow as expected, you can fertilize the soil lightly with an all-purpose, houseplant fertilizer.