Terrariums are garden containers, usually made of glass, that partially or fully enclose their plants. They help facilitate proper growth by trapping heat and moisture, and providing an optimal environment for plant growth. Best of all, it’s fairly easy to learn how to build your own terrarium, and it can be done with minimal time and budget.
In this article, we’ll look at what a terrarium is and what some of the benefits of having one in your garden are. After that, we’ll walk you through the process of building one, and show you just how easy this little DIY project can be.
Why Build a Terrarium
Before we get into the specifics of how to build a terrarium it’s worth taking a moment to look at why you’d do so in the first place. Terrariums are perfect environments for growing a variety of plants, and come with a host of benefits for your garden.
Takes Up Little Space: First off, terrariums can be a large variety of sizes and therefore can be made to take up very little space. All that’s needed is a glass container that lets light in, so you have tons of options. The size will dictate which plants you can grow, but small terrariums work perfectly fine with the correct plants.
Grows a Variety Of Plants: Terrariums can be made to provide a very humid and warm environment which opens you up to a large range of plants. Many people choose to grow tropical or other hard to grow plants in their terrariums.
Low Maintenance: Terrariums provide a lot of their own needs and recycle things like water making them very low maintenance. Many gardeners will find needing to water their terrariums as little as once every 1-2 months due to the natural moisture inside. With closed terrariums, which we’ll discuss later, this timeline is even longer, and many can survive quite a long time without input from you. This makes terrariums popular for those too busy or forgetful for traditional gardens.
Lots of Creative Options: Lastly, terrariums give you lots of options for getting creative. Many people will place decorations like rocks or twigs into their terrariums to create little ecosystems. Others will purposely introduce bugs into their terrarium to create a more dramatic scene. With a properly built closed terrarium you can build your own little ecosystem in your home and watch it develop.
Open Vs Closed Terrarium
In general, terrariums are separate into groups; closed and open. Open terrariums are exposed to the outside world and give easy access to the terrarium. Think of it like a jar without the lid, it’s open. These types of terrariums do best with lots of sunlight and infrequent waterings. They also tend to not have many issues with condensation or airflow.
Closed terrariums are the exact opposite and typically have a lid or other means to completely seal the terrariums. This traps in a lot more moisture, and also limits airflow, which can potentially lead to issues down the road. These types of terrariums should be in a more in-directly lit location to prevent burning the plants, but generally require less watering than an open one.
Open terrariums are best for plants that don’t like overly moist environments and enjoy some airflow. Closed ones are great for plants that don’t mind an enclosed space and like lots of moisture.
Good Plants for a Terrarium
Your plant choice will largely depend on the size of your terrarium and whether it’s open or closed. Larger terrariums will allow more larger plants while small ones are more limited. In general, make sure that no plant takes more than ½ of your terrarium space and leave roughly ¼ open to promote some airflow and to prevent overcrowding.
As mentioned, different plants will thrive in open vs closed terrariums. Here are a few good options for each.
- Air Plants
This is by no means an exhaustive list, there are dozens of other plants that will do well in either type. Make sure to make your plants care needs with the general environment of the terrarium. Closed is wet and humid with little airflow while open is still moist with modest humidity and more air flow.
How To Build a Terrarium
With all that out of the way, let’s now look at the steps to build your own terrarium.
1. Gather The Materials
The first step is to gather up all the materials you’ll need. Here is a quick checklist to help you gather all your items:
- A glass container or Jar
- Small Rocks/Pebbles
- Activated Charcoal
- Sheet Moss
- Potting Soil
There are some additional items you may wish to add, but the above is the minimum to get started with a successful terrarium.
2. Add a Drainage Layer
Before adding any plants you’ll want to set up proper drainage for your terrarium. Since your container likely won’t have drainage holes you need to manually create a place for water to drain lest you risk your plants getting root rot.
Start by adding 2-3 inches of small rocks or pebbles to the bottom of your container. This provides an area for water to drain to, and is essential for a healthy terrarium.
Once you have that, add about a half inch of activated charcoal on top of the rocks. This further helps with drainage, and also helps prevent any odors that might be present in the terrarium.
3. Add Your Soil Layer
Once your drainage layer is set up it’s time to create the soil layer. Start by adding a layer of sheet moss on top of the charcoal. This helps keep your soil from mixing into the rocks and charcoal below. Over time this “leakage” can reduce the amount of soil your plants have available to grow.
Once that’s done, you can begin adding your soil. You want to add at least a few inches of soil to provide room for root growth. The exact amount will vary based on your container size and the plants you’ve chosen. Make sure to leave enough room for your plants to completely fit inside your chosen container.
4. Add Your Plants & Decorations
Finally, it’s time to add your plants. Carefully remove them from their existing containers, and be sure to tease apart any bound roots. Then, gently place them into the terrarium and completely cover their roots adding more soil if needed.
You can also start to add in any decorations you might have. Things like twigs, moss, and stones are popular, but the sky’s the limit. Some people will place other items like shells or small figures to add some dramatic flair to their terrarium. Feel free to get creative here and really make it your own.
Lastly, give your terrarium a good dose of water. You want to make sure everything is moist, but not soaking wet. A spray bottle is good for this as it gives you better control over the water amount, and helps avoid dislodging or damaging anything in the terrarium.
Caring For Your Terrarium
Once your terrarium is built there are few things you’ll need to do to keep it healthy. Luckily, terrariums are well known to be quite low maintenance, and you’ll likely only need to spend a few minutes a month to keep it in tip top shape.
First off, most terrariums do well in in-direct to direct light with some evening shade. Open terrariums tend to do better in sunnier locations while closed ones should lean more towards the indirect side.
You should also periodically check the soil for moisture. If the top 2-3” are dry then add a bit more water into the terrarium. Terrariums typically maintain moisture much longer than potted plants, so expect to water them fairly infrequently. You also won’t need to fertilize a terrarium. It will naturally get all the nutrients it needs from the decaying soil inside.
If you notice condensation, especially on a closed terrarium, take the lid off to allow it to dry. Leave the lid off until the condensation is gone. You can also move your terrarium to an area with good airflow to speed up the process. With closed terrariums, you should do this every month to provide a bit of airflow to the closed environment.
Why Is Terrarium Condensation Bad?
On its own the condensation is not bad and no cause for concern. If it persists, however, it can make it more likely that bacterial diseases will take hold in your terrarium. That’s why you should occasionally promote extra airflow in your terrarium, along with allowing condensation to dry out.
How Long Do Terrariums Survive?
Technically, a well maintained terrarium can survive forever. With proper care, there are reported terrariums that have lasted for decades. Practically though, most people will see their terrarium last about 1-2 years on average.
How Much Water Do Terrariums Need?
Most terrariums need to be watered roughly once a month. Always check the soil beforehand, and water once it is dry. When watering, make sure the soil is moist but not soaked and swampy. There should not be any standing water on the soil, and it should not feel completely saturated.