Vases transformed into terrariums are typically best suited for single plants. Select a vase made from transparent material, such as glass or clear plastic. If the vase's opening is proportionally smaller than the rest of the vase, it will be challenging to assemble the terrarium, yet it will require less additional moisture to sustain the plant. A vase with a wider opening will require more frequent misting for irrigation. If the vase is too narrow for your hand, you will need a tool to assist planting, such as a long wooden dowel or long narrow spoon.
Clean the vase thoroughly with soap and warm water, rinse well and dry. If you fail to clean the vase you may be introducing harmful bacteria to your terrarium.
Pour a 2-inch layer of clean gravel into the bottom of the vase.
Add a 1/4-inch layer of activated charcoal over the gravel.
Place a 1- to 4-inch layer of potting soil over the charcoal. Use packaged potting soil, which you can purchase at the nursery, for houseplants.
Tap the bottom of the vase gently to settle the soil.
Make an indentation for the plant in the center of the soil using the dowel.
Remove the seedling from its container and gently shake off the excess dirt, yet don't disturb the plant's roots.
Gently place or drop the seedling in the vase, aiming at the indentation.
Plant the seedling in the indentation and cover its roots with soil, using the wooden dowel as a tool.
Spray the interior of the vase with water to remove soil from the plant's foliage and the walls of the vase and to moisten the soil.
Place the vase in a location with indirect sun. Don't place near a heat generating appliance or in a draft.