Updated: Feb 14, 2022
Setting up a terrarium is surprisingly easy. Once you’ve gathered up all of your materials it should only take you a few minutes to plant and arrange your terrarium. In this article, we’ll show you, step-by-step, how to build one of your very own.
Start by finding an attractive glass container.
Some people recommend that you use things like liter-sized soda bottles and other plastic materials, but we don’t recommend going down this path. After all, the point is to create a pretty display. Why stuff your beautiful creation into an ugly container? Put your soda bottle in the recycle bin and head to your nearest thrift store, dollar store, or weekend garage sale. You can find lovely inexpensive flower vases, glasses, mason jars, goldfish bowls and other glassware at these places for just a few dollars.
Choosing Your Plants — Air, Water & Light
The next step is to decide what type of terrarium you want to create. This means thinking about the types of plants you want to grow and where you intend to put your container. It boils down to a question of air, water, and light.
Do you want to build a closed, self-sustaining terrarium with a lid? Or will it be an open container?
For example, succulents need a different type of soil than most houseplants. They need loose, sandy or rocky soil, whereas most houseplants need sandy loam potting soil. Also, succulents want an arid, desert-like environment. They cannot be grown in a closed terrarium because it would become too humid for them. Even an open container may get too humid if it has only a narrow opening. Therefore, it’s best to grow succulents in an open dish-type pot.
On the other hand, ferns and many other tropical houseplants prefer the humidity they received in a closed kit.
It’s also important to think about where you’re going to place your terrarium after it’s planted. Some houseplants do well in low-light conditions but others need lots of bright, indirect sunlight. Make sure you have a spot that’s suitable for the plants you choose.
To sum it up, make sure all your plants have similar requirements for air, water and light so that they are compatible with each other.
What You Will Need
When you’re ready to build your terrarium, find a spot where you can spread out your container, soil, decorative materials and other ingredients so that you have plenty of room to work.
Exactly what items you will need depends on the type of terrarium you plan to create and how you want to decorate. Here are some basics, along with some ideas:
· Any size glass container (bowl, pitcher, Mason jar, flower vase, terrarium jar, etc.)
· Glass beads, Gravel, Sand, Pebbles or other similarly loose material
· Activated charcoal (Biochar)
· Potting Soil or Cactus Mix
· Sphagnum Moss or similar material
· Decorative Rocks or Glass
· Small watering can
· Garden gloves
· Spoon for working the soil
· Tweezers for gripping and placing plants
· Skewer and cork for tamping down soil
· Small plants (succulents, tillandsias, ferns, ivy, etc.)
· Decorative elements such as fairies, rocks, shells, or stones
Step 1: Layer your materials.
It’s very important to layer your materials in a particular order so that you have good drainage.
Layering helps to ensure that the roots of your plants are never sitting in water. However, closed terrarium systems do not have any way to expel excess water, and evaporation even in an open container can be slow so it’s critical that you do not over water your terrarium.
The worst thing for your plants is to allow their roots sit in water. It only takes an hour or so to suffocate their roots and kill them. Likewise, letting them sit in wet soil will cause the roots of your plants to rot.
Therefore, resist the urge to over water your terrarium. It’s always better to under water than to over water. If you find that you have under watered, you can always come back and add more water, but it’s almost impossible to remove excess liquid.
Layering also enhances the beauty of your container by adding colors and textures. Once you’ve got the essentials in place, have fun with your design and use whatever suits your fancy to fill in your container.
Most people start with a layer of pebbles or sand, followed by a layer of charcoal. We recommend a different method we learned from Laura LeBoutillier of Garden Answer. Using her method, we suggest you start with charcoal as your bottom layer and leave out the pebble/sand layer.
Whichever method you follow, charcoal is an essential ingredient in your terrarium. It helps keep your terrarium healthy by purifying the air and water inside your terrarium. It also control odors.
Step 2: Add Soil
Add an adequate amount of soil for your plants. If you want to, you can use soil as one of your decorative layers around the edge of the container. Or if you want to follow Laura LeBoutillier’s method, mound the soil in the center of the planting area and hide the soil by placing your decorative material around the mound.
Step 3: Create additional layers
Continue to layer your materials as you like. The deeper your container, the more layers you can build.
Step 4: Add more soil as necessary.
Make sure there is enough soil in your container so that when you place your plants in it, they will rise above the highest layer and be viewable from all sides. Keep in mind that your plants will settle slightly after watering, so allow extra height for that.
Step 5: Arrange your plants.
Space each plant so that it has room to grow. You may also want to leave some additional space between plants so that you can add decorative elements on top of the soil, such as stones and fairies.
Step 6. Cover the soil.
Fill in around the plants with sphagnum sheet moss or other soil covering.
Step 7. Finish off your design.
Place your fairies, rocks or other final decorations where you want them.
Watch our video on terrariums.
To properly maintain your terrarium, avoid these common mistakes:
This is the most common mistake and the worst one you can make. It is easy to over-water terrariums. One way to prevent it is to use a spray bottle instead of pouring water. It is easier to lightly water if you spray. If you do over water, try to absorb any extra with a paper towel. Leave the top off of your terrarium until it has dried out.
Too Much Light
It is easy to roast plants living in terrariums. The glass can act as a magnifier and burn your plants. It’s usually best to keep terrariums out of direct sun. Instead try to place them in bright, indirect light.
Too Little Light
Most plants need some light to survive. While there are lots of great low-light plants, there is no such thing as a no-light plant.
Too Close to Heater Vents
Keeping your plants too close to a heating vent can kill quickly. As with placing your plant too close to a window, putting it near a heater vent will quickly dry it out and toast it.
Letting Plants Get Scraggly
Keep an eye on your terrarium plants and when they get leggy, prune them back. To keep plants small you can also periodically remove them and prune the roots. Don’t allow the plants to touch the glass.
Not Removing Dying Plants
If a plant is sick, take it out immediately as it can infect other plants. Carefully dig the plant out with a small shovel, terrarium tool, or long spoon, being careful not to disturb the roots of other plants (as much as you can). Replace the plant with one of a similar size and light requirement, making sure to surround the roots with soil, leaving no air pockets.
Most terrariums do not need any fertilizer at all. Because you want to keep your plants small, you shouldn't feed them, which will cause new growth and the plants will quickly outgrow their confined space.
Choosing the Wrong Plants
While it is possible to grow almost anything in a terrarium, it is important to choose plants that will thrive in the type of terrarium you are creating. If you are making a closed terrarium, choose plants that like to be moist. Also, make sure to choose plants for the amount of light they will be exposed to. Low or medium light plants generally work best, but make sure if you get a medium light plant, you are actually giving it that light level.
Growing Succulents in Closed Terrariums
Succulents generally thrive high light and low moisture environments. If you put them in a closed terrarium, it will be far too humid for most to thrive. You can solve this dilemma by simply creating a glass dish garden without a top. Note that even a large jar will be too humid; you want air to be able to circulate around your succulents.
To keep your terrarium looking it’s best, you’ll want to occasionally clean it inside and out. You can use a damp piece of newsprint or a lint-free cloth. Do not use any harsh cleaning products on the inside of the terrarium because it may present a danger to your plants.
If you've chosen the right plants for the container you intend to use, you're already 1/2 way to success. The important thing about creating a terrarium is to have fun. Let your creativity be your guide and you are sure to enjoy your finished creation.