how to set up a terrarium (of any size)

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how to set up a terrarium (of any size)

Guest expert: Jira Sai, owner of Plant Corner in Harlem, NYC

If you want to have a more controlled environment for your rare houseplants but do not want to invest in a greenhouse cabinet then a terrarium is your best bet.

A terrarium is a mini garden in a glass enclosure that is a very cute and functional way to display plants. There are two kinds of terrariums, the type is based on the kind of terrarium plants that will call it home. A closed terrarium is best for a tropical plant like a philodendron that likes humidity and an open terrarium is perfect for succulents and air plants that like drier conditions.

People even make a carnivorous plant terrarium and fill the terrarium container with carnivorous plants. Some species like closed containers but it is better to use open containers so that they can eat insects.

A closed terrarium has its own ecosystem since it recycles the water and moisture in the air. It is great for those who do not want to monitor and water their plants often. The nice thing about terrariums is that you can easily make one with a jar or go all out with an aquarium tank.

We asked Jira Sai, owner of Plant Corner in Harlem, NYC for tips on how to set up a terrarium. She has a bunch of them in her store that displays her collection and a couple that are for sale too. She has great tips on how to make a DIY terrarium!

Like many plant lovers you started your collection during the pandemic, why did you decide to open a plant shop?

I had more time during the pandemic to care for plants and once I started it snowballed from there! And then I found out that my cousin in Thailand sells tropical plants, so I started selling online.

I would walk past this building on my way to work and I thought why not open a shop? That was in April 2021 and by August I quit my job as a middle school teacher and have been here full-time.

When did you get into terrariums?

I learned about terrariums right when I started taking care of rare plants. I liked how the closed container could maintain a humid environment which is perfect for rare houseplants. My first one was a 10-gallon fish tank.

What do you need to set up a terrarium?

You need a glass container that does not have a drainage hole. It can be a glass terrarium or made of acrylic, but that scratches easily. The first thing you have to put down is a drainage layer of rocks, pebbles, or gravel. I like to use leca. And then you cover that with a window screen or a thin layer of sheet moss and lay the substrate which can be potting soil, potting mix, or even pon.

I do not use soil because it breaks down faster and I don’t want to replace it. So I use a soil-less mixture of coco coir, wood bark, sphagnum moss, perlite, and horticultural charcoal. Each ingredient has a function—perlite creates air pockets, coco coir and moss help to hold moisture, and charcoal helps to absorb any toxins.

I try not to use preserved moss on the top layer that much since it will eventually get mold. Live moss can be bought online and that will grow and make the terrarium look pretty.

What is important is that the plant roots do not touch the drainage layer because that’s where the water will be. It will help prevent the roots from rotting while it is getting used to the environment. The roots will eventually grow and go into the drainage layer and that will be OK.

What kinds of plants can be added to closed terrariums?

how to set up a terrarium
how to set up a terrarium
how to set up a terrarium

Definitely high humidity indoor plants like philodendrons, creeping figs, jewel orchids, ferns, hoyas, and orchids. I like to add a small plant so that it can grow into the container. It is a good way to root cuttings too. These kinds of plants like indirect light so should be placed near a window or a grow light.

You can also have fun with the terrarium and add decorative rocks or small figurines. It is also nice to use plants with different colors, sizes, and textures.

how do you make a succulent terrarium?

how to set up a terrarium

You can use an open container and then it’s the same process—lay a drainage layer, window screen, and substrate. I like to use pon for succulents. Again, the roots shouldn’t touch the drainage layer and then the water should only be in that layer too. Succulents like bright light so it needs to be by a window with direct sunlight for most of the day or under a grow light.

What size container do you recommend for first-timers?

how to set up a terrarium

I would say starting with a medium container, a gallon jar, is easier than starting small. For a smaller container, you have to be detailed and specific on where to put each plant. For mid-size, you can just play with the area you have and the plants will have room to grow. You won’t be overwhelmed with all the work that you have to put into it and you won’t have to invest too much.

PRO TIP: These make great gifts for plant lovers 😉

What is the maintenance that you have to do with terrariums?

There should be water in the drainage layer at all times. A closed container has to be aired out every couple of days. For big terrariums, a small fan can be added to circulate the air. For one of my big terrariums, I installed a misting system because the plants in it need a super humid environment.

The terrarium setup I have is semi-hydro since it doesn’t have soil. So it does need to be fertilized. I use MSU orchid fertilizer mixed with Liqui-dirt and Joyful Dirt. Dyna-Gro is good too. Any fertilizer for growing hydroponic plants is fine, as long as it has micronutrients not just N-P-K.

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You can also add springtails, a type of isopod, that will eat the fungus and dead leaves. It will help keep the closed terrarium clean. 

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Plant Corner NYC

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