Closed terrariums are fascinating - trying to create a small ecosystem in an enclosed glass is a really interesting, fun and maaaaybe slightly challenging project.
Have you ever wondered how terrariums manage to survive without having access to the outside atmosphere?
In order to understand that, we have to know what plants need to survive. They need sunlight, oxygen, carbon dioxide, water and nutrients.
It can definitely take a little bit of trial and error to find the right conditions and balance for your closed terrarium, but when achieved, it can sustain itself for many years. We have a terrarium that we have never opened here in the studio that's nearly 5 years old! It's always a lot of fun to look at, throwing up random mushrooms and shoots throughout the year.
Let's have a look at how terrariums work.
Closed terrariums create their own ecosystems, basically their own little micro climate that they can survive happily in without any interference from the outside atmosphere.
In order to thrive, they need to have a very balanced ecosystem. It's important for them to have a good water cycle, correct light conditions and also a balanced carbon cycle.
There are other factors too that play a role in creating a balanced ecosystem, mainly leaf decomposition, nutrients, and of course, photosynthesis.
Sunlight
Terrariums will not survive in full sunlight, this creates an extreme Greenhouse Effect and absolutely everything in the terrarium will die very quickly. We have accidentally left terrariums in full sun over the years and they have died off in less than a day!
Terrariums do very well in indirect sunlight and also artificial light. This will help them thrive. We currently don't have any of our terrariums growing under artificial light. They are all grown in bright, indirect light and are happy.
Terrarium Water Cycle
How does water get into a terrarium?
Above is a diagram of the terrarium water cycle.
- Water is sprayed in to terrarium and the lid is put on top. It falls down like rain, seeps through the terrarium top layers of sand and gravel (if you have them in your terrarium) and soaks into the terrarium soil.
- Once in the soil, the terrarium plant roots take up the water as needed and it travels through the plant where it is used for photosynthesis, new cells and respiration.
- As the temperature slowly rises in the enclosed glass, the water evaporates from plant leaves and also the soil surface (known as evapotranspiration), becoming water vapour in the terrarium air.
- When the temperature slightly drops, the water vapour forms condensation on the glass.
- This water then slowly drips back down into the terrarium and the cycle continues.
- It is important to monitor the amount of moisture in terrarium soil. If it gets too dry, the plants will wilt and die and if it is over saturated, the plants will have very soggy roots and get waterlogged and also die.
- The best way to get a good balance is to pick plants that like the same level of moisture and to also monitor your terrarium in the first month after building.
The great thing about this is that when you get the amount of water right, you should hardly need to water your terrarium because it will have a lid on and is sealed, so the water cycle should just keep repeating itself!
Condensation formed on terrarium glass
Now that we have looked at the water cycles in terrariums, we're going to move onto the carbon cycle.
Terrarium Carbon Cycle
Carbon is an essential element for plant growth. Just as in nature, it is cycled between the air, soil and plants.
How does carbon get into a terrarium?
Carbon dioxide is in the the air and is taken up by terrarium plants through stomata, which are tiny opening on their leaves. The carbon goes inside the plant and is used for photosynthesis to create glucose.
The glucose is used by the terrarium plant for growth and energy. As the plants grow older, they store carbon in their tissues.
Plants will naturally shed leaves and also die over time. The carbon in these leaves is then released into the terrarium soil as the leaves slowly decompose, helped by bacteria and fungi present in the soil. the carbon is released back into the air as carbon dioxide.
The carbon dioxide is taken up by the plants and the cycle continues. This means that if kept sealed, the carbon in the terrarium remains constant and steady, which means the terrarium is self sufficient and and doesn't need any carbon from the outside world.
The Complete Terrarium Ecosystem
Creating the perfect conditions for a terrarium to thrive can be a balancing act! It is definitely a lot of fun (in our opinion!) trying to create it and it is VERY satisfying when you finally do.
Carbon, moisture and light levels need to balanced. Plants also play a very important part!
Every terrarium has its own unique atmosphere and environment,. This means that each one will require different care.
If you get the balance right, who knows how long your terrarium will grow for? Fingers crossed it will be for a VERY long time!
If you feel ready to go ahead and create your own little ecosystem, have a look at all of our ready to go complete closed DIY terrarium kits HERE.