How to Make a Terrarium With Our Easy Step-by-Step Guide

How to Make a Terrarium

1. Choose a Container

   Your terrarium container can be anything from low-cost and functional to expensive and sophisticated, such as a miniature Victorian greenhouse or conservatory.

   Almost any transparent (glass or plastic) container with a wide mouth (with or without a lid) will do. Suitable containers include aquariums, goldfish bowls, Wardian cases, cold frames, bell jars, tureens, apothecary jars, cloches, mason jars, glass cookie jars, and even large brandy snifters.

   A wide opening is key because it allows you to fit your hand inside to add drainage material, soil, plants, and decorative elements (shells, figurines, or ornaments). 

   Tip

   Open terrariums are less likely to experience problems with condensation and fungal plant diseases than closed terrariums.

2. Choose the Plants

   Most garden centers offer miniature plants for terrariums, sometimes in the section of the store containing fairy garden accessories. Choose plants that naturally grow best in high humidity and low light.

   Next, to introduce variety, pick plants from that group with various foliage forms and heights. Always keep in mind that they need to be small enough to fit in your container, preferably without touching the sides of the terrarium.

3. Add Drainage Layers

   A terrarium container does not have drainage holes, so you’ll need to create a drainage layer to keep water away from plant roots.

   • Start with a 2-inch layer of gravel or crushed stone at the bottom of the terrarium. A tall, narrow terrarium will require a deeper layer of drainage stones than a broad, shallow container.
   • Next, use a large spoon or trowel to add a 1/4-inch to a 1/2-inch layer of activated charcoal on top of the stones to help with drainage and control any odors (for a charcoal alternative, see Step 4).

4. Add Moss and Potting Mix

   Next, add a layer of sheet moss over the stones and charcoal to keep the next layer, the potting soil, from mixing in. The moss also adds visual interest to your terrarium.

   Alternatively, omit the charcoal in Step 3 and use live moss instead of the dried sheet moss, which controls odors similar to charcoal. You might also find lush, green live moss more attractive than a layer of charcoal.

   • With a large spoon or small trowel, add slightly damp, sterile potting soil on top of the moss. Do not use a potting soil mix with fertilizer already incorporated; terrarium plants don't need the extra fertilizer.
   • Add as much potting mix as possible—at least a couple of inches.
   • Make sure to keep the soil level low enough so that the plants will fit inside the container with room to grow but without touching the top of a closed terrarium.

5. Prepare the Plants

   Before planting, decide on the design of your terrarium. Choose spots for tall and short plants as well as mounds and dips in the soil to create interesting contours.

   • Remove the plants from their nursery pots.
   • If a plant is rootbound, tease the roots apart.
   • Use a pair of small garden snips to trim off some of the longer roots. Removing some roots, called root pruning, will retard a plant’s growth, which is essential when growing plants in the confines of a terrarium.
   • Trim off any yellowed or damaged leaves.

6. Add Plants

   Shake off any excess soil left on the plants. Use a long spoon or your fingers to dig a planting hole for each plant. Place each plant in its hole and gently pat the soil down to eliminate air pockets and secure each plant firmly in the potting medium.

   Tip

   If the terrarium has a narrow opening, use chopsticks, tongs, or long tweezers to place the plants into the terrarium and pat them in.

7. Decorate

   Decorating the inside of the terrarium is optional. Place small figurines, shells, decorative stones, or other whimsical accents among the plants.

8. Water the Terrarium

   Use a spray bottle or small watering can with a rose attachment and water so the plants are just damp, but not soaking wet.

   Dislodge any dirt clinging to the glass sides of your container and wipe them clean with newspaper or paper towel.

9. Maintain the Plants

   A terrarium requires basic but regular maintenance. Here’s how to keep your plants thriving: 

   • Light: Place the terrarium in filtered light away from harsh direct sunlight. If you don't have enough natural filtered sunlight in your home, use LED or fluorescent artificial lighting.
   • Moisture: Before watering, feel the soil to see if it's dry and needs water. Partially and fully enclosed terrariums retain water considerably longer than most potted houseplants. 
   • Air circulation: Inspect a closed terrarium for condensation. Take off the top at least once a month to increase airflow. Leave the top off until the condensation disappears. Also, take off the terrarium top if you added too much water. 
   • Pruning: Remove yellowing or damaged leaves and prune plants to a smaller size if they're growing too large for the container. 
   • Fertilizer: Never fertilize the plants in a terrarium and don't use potting mix with added fertilizer. Terrariums provide their nutrients through the natural decay of the potting mix.

How to Make a Terrarium With Animals

A terrarium with animals requires a whole different level of care and maintenance than a terrarium with plants only. 

Whether it’s reptiles such as turtles, amphibians such as salamanders, or insects, the terrarium needs to be carefully tailored to the specific needs of the species in terms of space, habitat, temperature control, etc.—in other words, you need to create conditions that mimic the animal's natural environment. Also keep in mind that the animals need feeding and other daily care, and the terrarium must be cleaned and sanitized regularly to prevent illness. 

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