Build a terrarium this winter

The terrarium is a mini garden in a clear glass jar.

It can be open or closed; closed terrariums have a lid on the tank. Both open and closed terrariums offer a great opportunity to showcase a single plant specimen or collection of small plants. One can build a great winter project and have fun with the kids.

A terrarium can create an environment for gentle tropical plants that would otherwise be difficult to grow in a typical dry home.

Dr. NB Ward is a 19th century London physician and English botanist who invented the terrarium. He discovered that fern spores germinate in a closed glass jar. He designed glass boxes called “Wardian Cases” that show fine plants. These cases adorned many homes of the era.


You can buy glass discs specifically designed for terrariums. However, a terrarium pot can be any type of clear glass or plastic pot: glass jars or bottles, fish or bowls, large goblets, or even clear plastic soda bottles. Open containers are drier and less prone to diseases that can occur in a high-humidity, closed terrarium vessel. The size of the tank is up to you; larger, larger-opening containers are easier to handle and plant.


The key to terrarium soil is to be sterile. The potting soil sold in the shops was sterilized; do not reuse garden soil or old potting soil. Due to the tropical nature of the terrarium, it is imperative that no bacteria enter the tank. Use garden gloves or wash your hands often while building the terrarium.

Plants are not meant to grow quickly; so no fertilizer is needed. At one time, experts believed that rocks, sand, or activated carbon were needed for terrariums to improve drainage (because there are no drainage holes in the terrarium tank). It is not necessary to add these layers. You can still add it for decoration if you wish. Adding moss is a good idea as moss can absorb excess water.


A variety of plants can be grown in the terrarium, including native and tropical plants. However, cacti and succulents are not a good choice; save these plants in a pot garden. How many plants and which one to choose depends on the size of the container and whether it is open or closed.

Look for plants that are dwarf in nature, grow slowly, tolerate high humidity, and tolerate low to medium light. Look at the texture of the plants and the different shades of green to maximize your interest. Think of decorations like rocks or small decorations used for fairy gardens.

Other tips

Terrariums need a bright place, but never expose them to direct sunlight, otherwise the plants will burn. If the plants grow too tall, pinch them back and remove dead foliage to prevent diseases that can spread quickly in a confined environment.

For more information, the Oklahoma State University Cooperative Extension has a video on YouTube:

And the Cornell Cooperative Extension in Nassau County has a fact sheet that lists the plants you can use in your terrarium:

For more information, visit or call 315-736-3394, extension 100.

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