Crafting and Caring for a Terrarium

A terrarium is a simple indoor project that is great for the winter months when many of us miss having our hands in the dirt! This terrarium was put together simply because I wanted to find a use for this large jar, but it turned out to be a lot of fun looking for small plants and bits of nature to build this miniature world. 

It's always best for the planet and your wallet to use what you have - but if you want to gather materials for this project, start with your local thrift store and your neighbourhood. Here's what you'll need:

• Glass container or jar 
• Gravel or small rocks
• Activated charcoal (optional)
• Potting soil
• Small plants suitable for your desired type of terrarium (see below)
• Decorative elements (optional)
• Spray bottle with water

Keep in mind when selecting a container that the narrower the opening the more difficult it will be to place materials and plants inside. Be sure to use potting soil, not garden soil. 

The layering is straightforward - add your gravel or rocks at the bottom, then activated charcoal if you are using it. The charcoal helps filter the water and prevent the odor and mildew buildup that may occur in a closed terrarium over time. Then add a layer of soil, the depth will depend on your plants and container. Last, add your plants and cover the soil with either decorative gravel or mosses, you can get creative here just don't leave the soil bare. Water your terrarium, and place in indirect light. 

Selecting Plants

There are two main types of terrariums and you will need to decide which you desire when choosing plants in order for them to thrive. Closed terrariums, like the one pictured above, are ideal for tropical, humidity loving plants. These are what you likely think of when you picture a terrarium. If you want to include succulents, you need an open terrarium. In general, try to select plants with similar water and growing needs since they will be sharing a container. 

 

Plants for a Closed Terrarium:

• Mosses
• Lemon Button Fern
• Birds-nest Fern
• Peace Lilies
• Miniature Orchids (humidity can cause rotting long-term for some types of orchids)
• Baby Tears
• Prayer Plant
• Miniature English Ivy (will need pruned over time)

 

Plants for an Open Terrarium:

Any dry adapted plant that fits in your chosen container can be suitable for an open terrarium, however it is very important not to over water. Since there is no drainage, water very sparingly. Succulents like the String of Pearls and Haworthia pictured above grow well in this open terrarium and tolerate drought for long periods of time between watering. Since there is not much soil in this terrarium, and no good way to drain excess water, I only give it a splash of water each 1-2 months. 

Moisture and Maintenance

Both types of terrariums are quite self-sufficient and resilient to neglect if you have selected appropriate plants. 

As mentioned, open terrariums for dry-loving plants should not need frequent watering. In this case, the container is not holding humidity but it also cannot drain from the bottom so do not overwater. You will only need to water occasionally to keep the plants thriving.

In some closed terrariums, they can be sealed and left indefinitely. The key is getting the moisture level just right when you start out, adding a little bit of water at a time and monitoring the moisture level over a couple of days when you first build your terrarium. There is one terrarium grown by David Latimer of England that has been sealed for nearly 50 years! However this is not everyone’s goal in creating a terrarium. 

I’ve found that opening the jar terrarium to “breathe” once every month or so has been beneficial. Some months I add a small amount of water if the soil has dried out, but most of the time it’s not necessary. Since the moisture that condenses on the glass is contained and eventually drips back to the soil, the air and soil remain moist, and the tropical plants and mosses have everything they need. A spray bottle is helpful for closed terrariums that aren’t completely sealed and do need a bit of moisture added regularly. After 6 months or a year, if you notice any yellowing leaves, you may want to add some diluted houseplant fertilizer to your terrarium either as a foliar spray or in regular watering. Try not to overdo it with water or fertilizers since your terrarium can't drain the excess.

 

My two biggest pieces of advice are:

1. Do not overwater. When first establishing your (closed) terrarium, add just enough water to moisten the soil, then wait and monitor the moisture/humidity in the container over the first 1-2 weeks adding water as needed to create an environment slightly less moist than a tropical greenhouse. This is not an exact science, but observing the condensation and humidity level over the first weeks will help you learn what conditions to maintain. 
2. Do not place your terrarium in direct sunlight, choose a shadier location with indirect sun. A closed glass container will heat up very quickly in the sun and potentially burn your plants (I learned this the hard way).

Try this project and let us know how it went! Happy growing.