Terrariums are closed environment miniature gardens. The closed nature of the container means that your miniature garden develops its own ecosystem. Whilst appearing complex, these beautiful terrariums are actually very simple to make and enjoy in your own home.
Today we’ll be learning how to make a DIY terrarium. This post will also provide you with a few maintenance tips to keep your DIY terrarium looking as fresh as possible.
- A clear glass container, such as a jar with a lid.
- Bonsai dirt
- A plant suitable for your terrarium environment
- Sphagnum moss
- Small stones
- Activated charcoal
- Decorative items (optional)
- Sand (optional)
- Moss (optional)
- Long-handled spoons
- Funnel (optional)
- Spray Bottle filled with water or dropper.
1. Choose Your Container and Plants
You may already have a suitable container around your home. Get creative! Most glass vessels can be turned into a terrarium. I have in the past even used a french press, where the outside stand had broken.
A few things to keep in mind when choosing a vessel. Choose a container with a wide opening. This is because if your opening is narrow, it will be harder to make your terrarium. It’s far easier to make a terrarium if you are able to fit your hand inside the vessel to move things around as needed. Glass jars with lids are a great choice. For something a little more ornate you could consider containers with gilding metal edging and various glass panes.
When choosing your plants, select those that are small, slow-growing and require minimal light. As your terrarium will be living inside your house, you don’t want a plant that will outgrow it’s container quickly or die due to the low lighting in most homes.
Likewise, choose plants that like being moist. The DIY terrarium we’re making will be closed, with a lid on top which means your container will become humid, as the terrarium is designed to do so. Think of it as a mini-greenhouse!
Good plants for your terrarium include Fittonia (nerve plant), maidenhair ferns, or peperomia. The Fittonia, or ‘Nerve plant’ as it’s commonly called is a striking addition to any terrarium.
2. Place a Small Layer of Pebbles on the Base of Your Container
These pebbles will provide a drainage layer for your DIY terrarium and prevent your plants from becoming waterlogged.
Ideally, this layer should be one-two inches within your container. Though any color pebble will work fine, consider using light-colored pebbles to add to the visual ‘layered’ effect of your finished terrarium. This way the pebbles will contrast with the potting soil.
As you begin the process of building your terrarium, think about your glass container in terms of ‘thirds’ The first third at the base of your terrarium is for the first three layers. The second is for your potting soil and the last third, the top of the container is for your plant to have room to grow in.
3. Add a Layer of Activated Carbon
This activated carbon is different from the kind used in fish tank filters but provides a similar purifying function. It’s also known as activated charcoal. Using activated carbon in your terrarium is optional, but will help your terrarium last longer and remain healthy.
Activated carbon purifies the soil, removing any build-up of toxins in the potting soil that long term, may harm your plants. It also tends to take away some of that ‘swamp’ smell if you decide to leave your terrarium open.
4. Add a Layer of Sphagnum Moss
Sphagnum moss is a particular type of dried moss that can be found at most nurseries or online.
This layer of your terrarium acts as a barrier between your soil, and the pebbles. Without the moss layer, when watered the soil will wash away down into the pebble layer.
Sphagnum moss is important in terrariums particularly for its ability to retain moisture. This is one of the reasons you will rarely have to water your terrarium.
5. Add Soil Layer and Your Plant
Gradually add your soil to your terrarium. I suggest using a fine soil such as a bonsai blend, as these soil mixes are designed for slow-growing plants with small root systems. This is handy to use in many various projects, including How to Grow and Care for A Bonsai.
Depending on the opening of your terrarium you may find a funnel or long-handled spoons come in handy for this step!
Once your dirt covers the layer of sphagnum moss by an inch, add your plant then cover the root system with more soil.
At this stage, if you want to make a beach-themed terrarium, use your funnel to gently add a layer of sand on the top. Alternatively, make a woodland terrarium by pressing some green moss down onto the soil.
Arrange your plants within your container carefully, considering the heights and colors that will be complementary to your overall scheme.
6. Add Your Decorations
Terrariums are like their own little world. As such, it’s a lot of fun to decorate your terrarium with a little figurine.
Pick some up from eBay cheaply, or from a thrift shop, or perhaps ask your child if they have a small toy they’d like to include in the terrarium. Let your imagination play.
Amazon has some great miniature figurines available for purchase. Miniature figures of humans add a little bit of wonder and character to your terrarium. If you find a lamppost figurine you could even make your own Narnia within your terrarium. Figurines of animals such as cows and calves are cute and make a peaceful scene within your terrarium. Some decorations come in bulk, which makes them cost-effective, particularly if you’re making a few terrariums to give as gifts.
Once all decorative pieces are in place, gently mist terrarium with your spray bottle and place the lid on the container.
Top Maintenance Tips
- Once the lid is on your terrarium, resist the urge to take the lid off. Doing so will disrupt the ecosystem that is developing inside.
- Misting on the glass is normal. This is caused by your plants releasing and absorbing moisture, and different times of the day will result in changes in the amount of mist inside your terrarium.
- Don’t place your terrarium in direct sunlight. It may look pretty on the windowsill, but if the sun comes out the glass will act like a magnifying glass and fry your pretty plants.
- Do place your terrarium in a bright place, away from direct light. They make lovely table centerpieces and are at home in bathrooms.
- Every plant eventually outgrows its container and will need repotting at some stage. However, you can gently trim most terrarium plants if you find they’re getting too big. But, if you care well for your terrarium it should last for several years.
- If your terrarium soil is looking completely dry, you may need to water. Water your terrarium with a spray bottle on mist, or a water dropper to the base of the plant. A little bit of water goes a long way.
Common Mistakes with Your Terrarium and How to Avoid Them
Terrariums are gardens under glass, and they allow you to design and create a tiny ecosystem of decorative elements and plants inside your new glass enclosure. Although they’re generally low-maintenance, there are some common mistakes many people make with them, and these mistakes can make them less successful. The biggest mistakes people make include:
Choosing the Wrong Plants
You can grow almost anything in your terrarium, you want to pick out plants that thrive in whatever type of terrarium you create. If you want to create a closed terrarium, the plants you pick out should have a moist environment to grow in. You should also pick plants that have the same lighting requirements, and low-light plants generally work best.
Every few weeks, you’ll want to clean the glass on your terrarium, both inside and out. If the glass gets too foggy or dirty, it can present a problem for light reaching the plants. Get a lint-free cloth or a damp piece of newspaper to clean the glass. Don’t use any harsh, chemical-based chemicals inside the terrarium because the chemicals could leach down onto your plants and damage them.
Failure to Remove Dead or Dying Plants
If your plants or plant in the terrarium are dying, diseased, or failing to thrive, you want to immediately remove it from the terrarium because the problems can move to other plants. Use a terrarium tool, small shovel, a long spoon, or chopsticks to remove the plant. You want to be very careful so you don’t accidentally disturb the roots of the other plants around it. Get a plant of the similar size with the same moisture and light requirements and replace it. Surround the new plant’s roots with soil, and be sure you don’t leave any air pockets.
You won’t need to add fertilizer to most of your terrarium plants. The goal is to keep your terrarium plants small and slow down their growth habit. So, you don’t want to feed them because this can influence the plants to outgrow the terrarium. If they do, you’ll have to carefully remove them and replace them with smaller ones again.
Keep an eye on your plants and don’t allow them to get overgrown and leggy. You want to see the decorative elements you put in your terrarium and admire each individual plant, and you can’t do that if they’re overgrown. If you want to keep your terrarium tidy and neat, you should trim your plants when they get crowded and overgrown. You can also prune the plant’s roots to keep them small.
It’s extremely easy to overwater a terrarium, especially if you leave it on the same schedule you water your houseplants. Use a spray bottle instead of a watering can when you water your terrarium to keep from adding too much. If you do add too much water, try to absorb any extra water with a paper towel. Leave the top off of your terrarium until it dries out a little.
Too Close to Heat Sources
Putting your terrarium too close to the heating vent or radiator can quickly kill the plants. If you put your terrarium near or on a radiator or other type of heat source, it’ll kill off most of your terrarium plants. Keep them in a place that won’t get many drafts either, because you want the temperature to be steady.
Too Little Light
Giving your terrarium too little light, even for low-light plants, can cause problems. Most plants need at least some light to do well. If your terrarium isn’t getting enough direct sunlight, you may need to put up fluorescent or grow lights to give the terrarium supplemental light. You can also put the terrarium by a window that gets a decent amount of indirect but bright sunlight.
Too Much Light
A lot of the plants that work well in terrariums don’t need very bright light. If you put these plants directly into the sun or in an area that gets very bright light, your glass can act like a magnifier that will burn your plants. Temperatures inside the terrarium can quickly get too hot, and this can cause your terrarium to get as steamy as a traditional sauna can. A lot of your plants can’t survive this kind of heat and humidity, so you want to make a point to keep your terrarium out of direct sunlight.
Plants That do Well in Terrariums
Terrarium by FarOutFlora / CC BY-NC-ND 2.0 Picking out plants that do well in terrariums takes a little research on your side. You want to pick out plants that like the same light conditions and water requirements.
There are several plants that thrive in low moisture and high light environments. If you put succulents in a closed terrarium, it’s too humid for them to do well. You can solve this by planting them in an open dish, uncovered garden. Even a large jar will be too humid because there isn’t a lot of airflow. However, there are a few plants that do well in terrariums, including:
1. Aluminum Plant
The aluminum plant is native to Vietnam, and it likes to be in terrariums with warm temperatures and low-to-medium light. The leaves will give you pretty iridescent white markings that make it stand out. The plant will also grow fairly quickly in your terrarium, so it’s essential that you pinch it back from time to time. It’s easy to root, and it likes to have regular water in the spring and summer.
2. Prayer Plant
The red-veined prayer plant is a very stunning plant, and it’s a rare houseplant. This plant gets its name because it’ll fold up the leaves at night like it was praying. If this plant doesn’t get enough light, the leaves will stay folded up during the daytime too. These plants like to be warm, so they won’t do well next to a chilly draft or cold window. Put them in a terrarium that gets medium to indirect light, and you should water them regularly in the spring. You get green leaves with white markings.
3. Artillery Fern
This fern isn’t an actual fern, but it’s a member of the Pilea family. They get the name artillery fern because it’ll shoot seeds and make a popping sound. You can hear this popping sound at a distance. Despite this plant’s explosive trait, the plants are very delicate. They’ll bring an interesting texture to your terrarium. You will find that it grows easily and it should thrive with minimal care on your part. Put them in medium to indirect light with medium water.
4. Polka Dot Plant
Polka dot plants are very bright and cheerful when you add them to your terrarium. It comes in red, pink, and silver coloring. It’s very easy to care for once you get it established. If it gets too spindly or leggy, you may have to pinch it back to keep it small enough for your terrariums. It likes indirect, but bright lighting to thrive, and you should water it regularly in the spring and summer months and back off in the winter. It’ll produce green leaves with pretty white markings as it grows.
There are over 1,000 cultivars of this plant available. The more common cultivar has leaves that are blushed with a little red or they’re all green. This is a very slow-growing plant, and this is what makes it great for your terrariums. This can produce a small flower spike as it grows, and they can add a welcome pop of color in the terrarium. They like low to bright light as long as it’s indirect so it doesn’t get too warm. They need relatively little water, and you want to make a point to not overwater it to keep it healthy.
6. Button Fern
This button fern is very visually-appealing, and it’s a smaller plant. It originates from New Zealand, and it’s a nice plant for beginners because it’s drought-tolerant and hardy. You will get a slightly mop-headed look to it, but it offers a delicate and elegant look at the same time. This plant does well in filtered light to full shade, so keep it out of bright sunlight. You should water it sparingly, and it does well with light weekly watering sessions. You get deeper green foliage too. The small rounded leaves grow in slender stems and trail along the bottom of the terrarium.
You can add a lot of texture and visual interest to your terrarium with this plant. It has very thick and shiny leaves with an array of colors, including gold, green, and salmon hues. The gold dust variety has very narrow leaves on it with different amounts of gold coloring, depending on the cultivar you pick. This isn’t a very well-known plant for terrariums, but it does well in open-jar concepts. You should place it in a spot that gets indirect but bright and dappled light, and you should water it occasionally to keep it moist.
8. Baby Tears
This is a very small plant that has a lot of common names. You may hear them called peace-in-the-home, angel’s tears, Pollyanna vine, mind-your-own-business, Corscican’s curse, and mother of thousands. Under the correct conditions, this plant can be invasive because it grows so rapidly. It can take over entire gardens. However, it behaves in terrariums as a low-growing plant. It loves to have bright but indirect light, and you should keep the moisture levels consistent. It’ll produce creamy ivory flowers that lighter green foliage.
The golden pothos vine can look unremarkable as a houseplant, but it looks wonderful arranged in a terrarium. This plant has a reputation as an indestructible, bulletproof houseplant, and this is enhanced more in a terrarium setting. You will have to prune it back every few months to ensure that the plant doesn’t get unruly, and it should look good for years. It’s also very easy to propagate by rooting the stems in water. You need indirect but bright light for this plant to do well, and it needs relatively little water. Don’t overwater it, and enjoy the white markings on the green leaves.
10. Creeping Fig
Creeping fig is one plant that offers variegated, small heart-shaped leaves. It’s an easy indoor vine plant to grow. It makes a good addition to any terrarium. This is a climbing vine, so you will have to make structures in your terrarium for it to creep up as it grows. It could be fun to try in a larger terrarium. If you want to propagate a new plant, all you have to do is root it in branch-cutting water. It does best in partial to full sun, and you should water it occasionally. It’ll offer pretty green foliage as it grows.
Terrarium Frequently Asked Questions
My Terrarium by starbright31 / CC BY-NC-ND 2.0 If you’ve never had a terrarium before, it’s common to have several questions, and we’ve rounded up a few of the most frequently asked ones people have below.
1. Should your terrarium be open or closed?
If you pick out open terrarium design, your plants need a drier environment and circulating air. Hens and chicks, aloe, air plants, and cacti all do well here. If you pick out a closed terrarium, you’ll need plants that like a closed space with more moisture. Both designs work well as long as you have the correct plants.
2. Are terrariums self-sustaining?
A terrarium is essentially self-sustaining as a plant ecosystem. It has living plants inside, so it can be self-sustaining, as long as the plants are thriving and you set it up correctly. You will have to perform routine maintenance too to keep your plants smaller.
3. Why does mold or fungus grow in the terrarium?
Higher humidity levels can make excellent conditions for mold or fungi to establish or grow. This is especially true if your terrarium is overcrowded. You want to nip problems in the bud by promptly removing any dying or dead foliage. Another point you have to do is keep the glass clean. If it’s too far gone, you’ll have to empty out the entire thing and start over.
4. Do closed terrariums need a lot of sunlight?
If you have a closed terrarium, your plants require a high amount of light, but it shouldn’t be direct light. You should check your terrarium every few days to look for condensation on the glass. If you see it, you should open the container and leave it for a while to allow the excess moisture to evaporate to make it healthier for the plants.
5. What is the average lifespan of a terrarium?
The lifespan of an average terrarium will ultimately depend on how you take care of it. Your environment plays a role as well. The average lifespan for your terrarium is around two years, but it can last longer with the proper care and maintenance.
6. Can animals live in a terrarium?
A terrarium habitat could include fungi, plants, isopods like pill bugs, lichens, spiders, beetles, earthworms, reptiles like turtles, amphibians like salamanders, crickets, and more.
Terrariums thrive on neglect, so they’re one of the easiest house plants to make and enjoy. We hope you have a blast making a DIY terrarium, we certainly did! Terrariums are one type of container gardening that can save you space and exercise your creativity. Terrariums are one of the many options available for indoor plant keeping and make a striking feature in your home.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.