Terrarium Care

Caring for and maintaining a terrarium is similar to caring for regular house plants, but there are very notable differences. Let's look at 3 different types of terrariums.

Open Air Succulent Terrarium

Succulents should never be put into a closed container, especially one with a tightly sealed lid. As such, all of the succulent terrariums I have are open air. Since terrarium containers don't have a drainage hole, they can't be watered in the same way as a regular potted plant. Because of this I use a drainage layer with a barrier of screen, or geo-textile fabric. The barrier is meant to keep the soil from touching the water after it has drained following a watering. The water then dissipates through evaporation over time. To further assist with this process I've developed a 3D printed ventilation tube that I now use in all of my succulent based setups.

Since you can't water a terrarium like you would a potted plant (via a bottom watering, or soaking, or thorough watering from above, you have to be more selective with how you water. I prefer to water using a squeeze type bottle so that I can "spot water". This means only watering one, or some, of the plants in a container at a time instead of simply flooding the entire container all at once. This is because some plants require more regular watering. For example a sedum might want water every week or 2, whereas a cactus might only need water once a month. How do you know? This may take some effort on your part to research what plants are in your container. More often than not I water ALL of the plants in a terrarium at the same time. But in others, such as one with a Lithops (VERY drought tolerant) I try not to let that one get as wet.

Soil becomes hydrophobic over time, so I will often use something like a chopstick to poke a hole in the surface near the plant I want to water in order to help guide the water into the direction of the roots rather than across the surface where it might eventually run down the sides of the container.

Summary: Pay attention to the plants, take time to learn about their watering needs, spot water as well as you can.

Open Air Tropical Terrariums

Care for these are very similar to caring for a typical indoor house plant. The drainage layer acts as a place for water to drain out of the soil and you don't want to give it so much water that the drainage layer fills completely with water. Let the soil dry in between watering. The time it takes for this can vary greatly depending on your environment.

You can visually inspect the soil and drainage layer through the glass to check for moisture. You can also lift the container to see how light or heavy it is. A dry terrarium is much lighter than a fully watered setup. If there is moss in the terrarium you'll want to spray/mist it to keep it somewhat damp, but not drenched. Moss does not like to sit in a bog, but it also doesn't like to be dry. 

Summary: Similar to indoor house plants, ever 1 to 2 weeks, but never water on a rigid schedule (such as every Saturday). Look at the condition of the plants and base your watering on that.

Closed Tropical Terrariums

These are setups with a lid. Some can be very airtight, such as a twist off lid on a jar, and some are only partially air tight such as a piece of acrylic or glass that sits on the surface. These coverings allow for moisture to stay trapped within the setup. That means you need to water far less. You can likely go a month, or several months in between watering. And, even when it is time to water you may only need to spray/mist all of the plants instead of pouring in water.

Summary: Closed containers need far less watering once a moisture level is established. Pay attention to condensation (or lack their of) and water in the drainage layer. Stick to misting the setup unless it looks very dry, then give it limited water.