by Tina Potter
Terrariums are a great way to garden indoors and in small spaces. There are endless options when it comes to the type of container that can be used as a terrarium. Just make sure it’s made of clear glass or plastic so light can penetrate to the live terrarium plants. Glass containers can be found in a wide variety of places and need not be specifically designed to hold plants. Vases, jars, bottles, fish bowls and aquarium tanks are all good choices for terrariums. Second hand stores such as your local Salvation Army, Volunteers of America and Goodwill hold a wide variety of glassware suitable for terrariums often at deep discounted prices. Small glass containers are great for that one special plant that you would like to showcase. Make sure to use the appropriate plants suitable for terrarium life. Most tropical houseplants that have a slow growth rate and small size are suitable for terrarium life. A wide variety of ferns and mosses are also good choices. Carnivorous plants such as the Venus Fly Trap make good terrarium plants too. Be careful not to mix plants that have different needs. For example, the Venus Fly Trap should never be planted in the same terrarium as a tropical house plant. Both have different soil, light and watering needs. Succulents and cacti cannot handle the humid environment a terrarium with sides creates, even when planted in sand. Be creative, but make sure to factor in the care needs of the live terrarium plants when creating a terrarium.
Glass container (clean and dry)
Bottom drainage layer (Josh's Frogs False Bottom)
New Zealand Long Fiber Sphagnum Moss (moistened)
Live Terrarium Plants
Optional decorative items such as wood, rocks, miniature garden items
Tools (such as planting tongs)
Water spray bottle
Distilled, reverse osmosis or bottled water
You can additionally read a Guide to Order Supplies.
Step 1: Drainage layer
Line the bottom of the container with Josh's Frogs False Bottom. The purpose of this layer is to provide drainage and prevent the plant roots from sitting in water and causing rot and death to the plants. The drainage layer should be ½” to 1” deep, depending on the height of the container. Next, apply a thin layer of horticultural charcoal. This will help filter the water and keep the terrarium fresh. Make sure you rinse the charcoal with cold water before adding it to the terrarium. It’s coated with a fine black dust which will cling to the inside of the glass and will be hard to remove after the terrarium is finished.
Step 2: Soil layer
Add a layer of moist long fiber sphagnum moss. This will prevent the soil from falling down into the drainage layer at the bottom of the container. Next, add a layer of terrarium soil. Terrarium soil is specially mixed for plants in an enclosed environment. It’s lighter and allows the roots to breathe. Top soil should never be used as it will suffocate the plants. The soil layer should be double the depth of the drainage layer and also deep enough for the plant roots to be covered. The soil layer can be flat or it can be higher in some areas and lower in others to provide visual interest and a more natural look to the terrarium. Decorative rocks or wood pieces can be added at this time and may also be used to terrace different levels of soil.
Step 3: Plants
Now it’s time for live terrarium plants. Arrange the live terrarium plants before placing them in the terrarium so you have a good idea of how you want the plants to look. If the terrarium will be viewed from all sides, place taller plants toward the center. If it will be against a wall and only viewed from one side, place taller live terrarium plants toward the back. Medium height plants are planted next and then shorter plants such as mosses and low growing ground cover plants on the outer edge closest to the glass. Carefully remove the plants from their pot and remove excess soil from the roots. Use your hands or planting tongs to insert the plants into the soil. Firmly tamp down the soil once the plants are in. Now is the time to add any additional decorative items you want to add.
Step 4: Watering
Once all live terrarium plants are in place it’s time to water. Never use tap water in your terrarium. Tap water has minerals in it that can slowly build up in the soil and harm your plants. It also leaves a nasty film on the inside of the terrarium glass that’s hard to clean off. Use only distilled, reverse osmosis, or bottled water. Water the live terrarium plants and soil with a water spray bottle until the soil appears moist and excess water begins to drain through the moss layer to the drainage layer at the bottom. Take your time when watering and give the water a chance to absorb into the soil. It’s better to underwater than to overwater at this point. The goal is not to have excess amounts of water sitting around in the drainage layer at the bottom. Wipe excess water off the inside of the glass with a soft cloth or tissue.
Step 5: Care
Place the terrarium in a bright place out of direct sunlight. Direct sunlight will bake your plants and will mean certain death for the entire ecosystem of the terrarium.
Don’t overwater the plants. The trick is to avoid pooling water in the drainage layer at the bottom so water plants only until the soil is moist, not wet. If the glass on the inside of the terrarium has some fogging or light condensation, this is normal. If the condensation is constantly dripping, this might be an indication that you are overwatering. If you have a covered container, remove the cover and let the soil dry out a little before replacing. Condensation can be gently wiped off with a soft cloth or tissue.
All plants need to be pruned so don’t be afraid to trim off branches and leaves as the live terrarium plants grow. You can use some of the clippings to start new plants as the humid conditions in a terrarium are perfect for propagation.
Keep the terrarium at room temperature.