terrarium making

Q: I thought it would be a fun project for my elementary school age kids to start some terrariums over the summer. Do you have any suggestions?

A: A simple terrarium is a transparent container that allows plants to grow. It can be closed or opened in the air. Sealed terrariums let in light and heat, but water and moisture are recycled inside the container. Like all other houseplants and outdoor plants, a successful terrarium requires matching the plants to the environment.

Select the type of container you want to use. Inexpensive glass jars and bowls are often available at thrift stores and garage sales. Old aquariums also work well. A leaky aquarium can still make a good terrarium. Lost or broken glass can be replaced with plastic or screens. The aquarium may also have matching light fixtures in which you can install a grow lamp.

Once you have your container, go shopping with the kids at the local greenhouse. The staff will be able to help you choose the right plants for the container based on the size of the container and whether it has a lid or is open to air. Young and young plants of all kinds can be grown in a terrarium, but to maintain a long-lasting terrarium, use plants that have matured as young plants.

(Natalia Lebedinskaya/Shutterstock)

Large containers are easier to maintain. If the opening is too small to allow a hand to enter the container, it will be difficult to install and maintain, which is fine for some people who like a challenge. The closed ground will have high humidity in which tropical plants will thrive, but you need to pay attention to problems with diseases that can quickly develop at high humidity.

The type of plants used will determine the type of soil in the terrarium. Cacti and succulent earth will require sandy soil and an open-top terrarium. For most tropical plants, a mixture of peat and perlite soil works well. Tillandsias do not require soil for roots while Venus flytraps require very moist soil.

Since there are no drainage holes in the terrarium, water circulation and drainage must be taken into account. In a closed system, water evaporates and diffuses by plants into the air. Then it condenses on the container and pours back into the tank. In the open system, the drainage system prevents the roots from sinking.

We build a terrarium in layers. The bottom area is the tank layer which will be large pebbles or marbles to allow water to accumulate in the tank. The tank should be deep enough to hold the water needed to create moisture and water circulation for the plants being used. A dry soil tank will have a smaller tank than a wet soil tank. Then we put a screen to prevent soil particles from clogging the tank. The next layer is a layer of activated charcoal that filters the water flowing into the tank. Place another screen over the charcoal to prevent it from clogging. Next is the soil mixture for the type of plant we are growing. It can be a sandy mix for succulents, a mix of moss for tropical plants or an orchid mix for some types of orchids.

Someone makes a terrarium
(ivan_kislitsin/Shutterstock)

Finally, on top of the soil mix, we can install decorative items including fine sand, pebbles, crushed glass, rocks, crystals, shells and assorted bedspreads.

Sealed terrariums need to be kept out of direct sunlight, otherwise they may overheat and overcook the plants. Even open terrariums need to be carefully monitored for a while to see how they interact with the general environment.

Aquariums are a great way to create a beautiful centerpiece. They require some maintenance and sometimes they may need to be rebuilt, but that’s part of the fun of terrariums.
I’ve added a video on the basics of creating an aquarium, now available on the Greener View YouTube channel. Don’t forget to go to greenerview.com for a link to the Greener View Gardening book and use the “newspaper” promo code to get the PDF half of the book.

terrarium tip paper

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