7 Mistakes to Avoid When Caring for Your Terrarium - Backyard Boss
We are reader supported. External links may earn us a commission.

7 Mistakes to Avoid When Caring for Your Terrarium

Terrariums are a fun and trendy way to display houseplants using a variety of vessels. Closed terrariums are traditional, but open or dish terrariums are also popular, especially for plants such as cacti or succulents that prefer a dry environment.

Since terrariums are mini-ecosystem, they don’t require much maintenance and can even thrive under artificial light. Terrariums are an excellent environment for growing some of your more picky plants, such as carnivorous plants. Still, it’s essential to avoid these few key mistakes.

1. Choosing the Wrong Plants

person placing a plant in a terrarium
Image credit: Anna Schvets via Pexels

When choosing plants or introducing new plants to your terrarium, it’s critical to carefully select them for the vessel you chose. Closed terrariums are ideal for humidity-loving plants, such as ferns, crotons, ivy, mosses, begonias, and carnivorous plants. Open or dish terrariums are perfect for those with medium to low-humidity needs, such as succulents, air plants, and snake plants.

Selecting plants with similar care needs is vital for the health of the plants. In addition, be mindful of the size of the plants compared to the terrarium. Generally, low and dense-growth plants are the best as they are less likely to quickly outgrow the small environment. Taller plants, such as Syngoniums, Bromeliads, and prayer plants, flourish in terrariums but, due to their size, need large containers and regular pruning.

2. Using Colored Glass or Plastic

Looking a terrarium under a magnifier glass
Image credit: cottonbro studio via Pexels

When selecting glass or plastic for your terrarium and the cover, avoid translucent or colored material. The more transparent the glass or plastic is, the higher quantity and quality of light it allows to pass through, thus increasing photosynthesis. Since light is the number one factor affecting indoor plant growth, it’s crucial to use transparent glass or plastic to allow your plants to flourish.

3. Using the Wrong Soil Medium

Adding soil to a Terrarium
Image credit: cottonbro studios via Pexels

When caring for your terrarium, it’s necessary to select the soil medium based on your plants’ needs. This is another reason to choose plants with similar requirements. For tropical plants, use one part peat moss or coco coir with one part nutrient-rich potting soil. For arid plants, mix two parts sand and two parts potting soil with one part pumice. 

4. Wrong Location

Terrariums Under Grow Lights
Image credit: Anna Shvets via Pexels

Selecting the right location for your plants is crucial for their health, and a terrarium is no different. Terrariums thrive in bright-light areas, but too much direct light can be detrimental to the health of your plants, especially in a closed environment. Direct sunlight can increase the temperature to a dangerous level within the terrarium, causing heat damage to the plants and also allowing too much moisture to build up. North and east-facing windows are ideal for closed terrariums, while cacti and succulents in dish terrariums will benefit from the direct sunlight of a west or south-facing window.

Placing terrariums in a low-light situation also adversely affects most plants. If your terrarium isn’t receiving enough light, you can supplement it with artificial light. A 100-watt bulb placed near the terrarium or fluorescent tubes placed over the terrarium should be sufficient as a supplement for most plants.

In the winter, be mindful of how close your terrarium is to heat sources and move them if needed. Heating units can drastically increase the temperature within the container, harming or killing the plants.

5. Too Much Water

Spraying plants in a terrarium
Image credit: Karolina Grabowska via Pexels

Your terrarium plants are more likely to suffer from you over-tending them. And overwatering is just about the worst mistake you can make, especially with a closed-environment one. Many closed terrariums only need water every three to six months. However, the frequency can vary greatly depending on various factors, including plant and soil type. 

For example, humidity-loving plants in open or dish terrariums often benefit from weekly misting. Since there isn’t drainage in terrariums, when you do water, do so lightly. If too much moisture builds up inside a closed terrarium, remove the cover until the condensation evaporates. Then, sit back, relax, and enjoy your beautiful plants.

6. Using Fertilizer

Image credit: Maud Bocquillod via Unsplash

Fertilizing is a houseplant chore you can forego for terrarium plants. Fertilizing your plants will only make them grow faster, meaning they will outgrow that adorable vessel in which you so carefully placed them. Nutrient-rich potting soil keeps your terrarium plants thriving without the need for fertilizer.

If, after a year, the plant’s growth slows without any other apparent issues, you may need to apply light fertilization. Use a water-soluble houseplant fertilizer at a quarter of the rate recommended.

7. Not Removing Overgrown Plants

Women putting a nerve plant in a terrarium
Image credit: Karolina Grabowska via Pexels

Even a well-planned terrarium will eventually become a jungle of plants. Regularly prune your plants to prevent them from running out of space or choking each other out. Prayer plants and Syngonium, for example, are easy to propagate, making a trim a fun way to create more. 

Most plants will outgrow the space at some point, so it’s important to remove them when this happens. In addition, any time you notice a diseased plant, act fast and remove it. Always use sterilized tools, so you don’t introduce or spread disease to the environment.

Caring for Your Terrarium

Terrariums are a fantastic way to aesthetically display your most finicky plants. Homes are notorious for having low relative humidity, which is less than ideal for most houseplants. Terrariums fix that problem by creating a perfect humid ecosystem, but avoiding a few key mistakes is crucial. Once you have a handle on caring for your terrarium, you’ll be raving about how well your plants are growing.

Do you have a terrarium? Share your tips or tricks in the comments!