How to Make a Terrarium

Easy to make and maintain, terrariums are an excellent way to keep your hands working with plants in the garden off-season.

by Dani Yokhna
Create a woodland terrarium to keep your hands working with plants even when cold weather sets in. Photo by Stephanie Staton (
Photo by Stephanie Staton
Create a woodland terrarium to keep your hands working with plants even when cold weather sets in.

Difficulty: Easy
Time: 30 minutes to 1 hour

Breathing new life into your home during winter not only helps brighten your spirits, it also allows you to get your hands dirty and feed your craving to tackle gardening tasks without ever stepping foot outside your back door. If you’re wondering where I’m going with this, look no farther than your favorite clear, glass or plastic container: your terrarium foundation.

You can grow many types of plants—from succulents to mosses—in a terrarium, but moisture-loving plants, such as mosses and ferns, benefit from closed containers or ones with small holes that retain moisture, resulting in higher humidity levels than those in bowls or vases. Containers with large openings tend to expose the plants to the home’s dry, forced air, which can be tough on moist plants. While dry, forced air is more conducive to growing succulents and cacti, these plants can require more care.

From the Pages of Hobby Farm HomeWhen selecting plants, the University of Missouri Extension recommends looking to low-growing, dense plants, such as African violets and impatiens, but also concedes that larger varieties will suffice when pruned regularly. The MU Extension also recommends choosing a plant theme—woodland, tropical or desert—and sticking to it: “Don’t mix plants requiring widely different light, temperature and moisture conditions. Succulent plants and cacti are less desirable for terrariums because moist conditions promote rot. Don’t mix desert plants with moisture-loving tropicals.” (Find a list of recommended terrarium plants on the MU Extension website.

Terrarium Materials

  • large, clear, glass or plastic container with small opening or clear lid
  • pea gravel or other small gravel
  • activated charcoal
  • cloth weed barrier (optional)
  • moss or lichens
  • sterile potting soil
  • low-growing, dense plants in varied heights and textures
  • decorative stones or pebbles
  • bulb sprayer

Step 1: Clean terrarium container.
Use a solution of 10-percent bleach and water to sterilize your container to eliminate any potential pathogens. Rinse thoroughly to remove all bleach residue.

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Step 2: Create terrarium base.
Gently pour gravel into the bottom of your container, filling with about 1 to 2 inches gravel for larger containers or slightly less for smaller containers—the base should not exceed 1/5 to 1/4 the total volume of the container. Sprinkle 1 to 2 tablespoons activated charcoal over gravel and stir gently to thoroughly mix. (The charcoal will help prevent the buildup of microorganisms, such as algae, in the substrate and reduce odor.) Cut your barrier cloth to fit the area on top of the gravel and lay in place. (If you use fine gravel, the cloth is not necessary—its main purpose is to prevent soil from sinking through your gravel to the bottom of the container.)

Step 3: Insert moss.
If you’re starting with dry moss, soak it for at least 10 to 15 minutes prior to use. If your moss is damp but slightly stiff, spritz with water for pliability. Based on the size of your container, pull apart moss into long strips that are 2 to 3 inches wide. Place the moss around the edges of the cloth barrier, with the green tops facing the glass and slightly overlapping the ends.

Step 4: Add soil.
Pour in just enough soil to cover the cloth barrier and push it up the sides of the moss roots. Do not add fertilizer; you don’t want plants growing by leaps and bounds and overflowing your container.

Step 5: Place plants.
Choose plants of varied heights and stagger them to fill out the container—odd numbers work best for a natural look. Position your plants and fill in soil around roots to hold in place. Trim any stems or leaves that protrude from the top of the container or that interfere with the design of your arrangement.

Step 6: Compress soil.
Once your plants are where you want them, finish filling in with soil, creating an even layer, and compress it with your hand or a stick. Spray with a small amount of water to help soil settle and stay in place (optional).

Step 7: Hardscape plantings.
Use decorative stones, pebbles and leftover moss to create paths and features, intermixing materials for a more natural-looking tableau. (Bonus: A layer of pebbles on your soil creates a dry surface to repress fungus gnat.) You can also use small sticks to emulate downed trees or benches. (Cornell University Cooperative Extension recommends doing this before planting, but because I was unsure of where I wanted items, I waited until after my plants were in position to place them.)

Step 8: Water thoroughly.
Brush soil from leaves. Add water gradually and evenly over the surface, filling no more than halfway up the gravel.

Display your terrarium in a well-lit area that doesn’t receive direct light: Intense light could create a greenhouse effect and burn your plants. Rotate the container occasionally so plants grow evenly instead of toward the light source. The optimal room temperature is 70 degrees F.

Water weekly as needed to maintain a moist surfaceÑbeads of moisture on the glass indicate a well-watered medium. Fog on the glass indicates overwatering, in which case, you should let the container dry out for one to two days by removing the lid or placing the container in a slightly warmer area before returning it to its original location and resuming waterings. Prune plants as needed to encourage a fuller shape and maintain a small size.

Special thanks to John Michler, of Michler’s Florist, Greenhouses and Garden Design in Lexington, Ky., for his fun and informative terrarium class.

This article originally appeared in the January/February 2013 issue of Hobby Farm Home.


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