Terrarium Care and Tips: 10 Mistakes to Avoid

Terrariums, also known as gardens under glass, enable you to design and create tiny ecosystems of small plants and other decorative elements inside a glass enclosure. Terrariums bring contained, natural elements to your home or office and can last several years with proper care. Terrariums are generally low-maintenance and require less attention than most other house plants. However, they do require occasional maintenance.

To maintain a healthy environment for your plants, you should avoid these 10 mistakes.

Too Much Light

Most plants suitable for terrariums do not require extremely bright light. If placed in direct sun or extremely bright light, terrarium glass can act as a magnifier and burn the plants. Temperatures inside the terrarium can rise quickly; before you know it, the terrarium can become as steamy as a sauna. Most plants can't tolerate this heat, so it's best to keep terrariums out of the direct sun.

Too Little Light

While too much light can cause problems, most plants need at least some light to survive. If your terrarium is not receiving enough indirect light, use grow lights or fluorescent lights to provide supplemental light or place the terrarium closer to a window that receives good but indirect light.

Too Close to Heat Sources

The heat generated by a radiator or heating vent can kill your plants quickly. If you place your terrarium on or near a radiator or other heat source, most terrarium plants will not survive.

Overgrown Plants

Don't let terrarium plants become leggy and overgrown; you want to be able to admire individual plants and see the other decorative elements inside the terrarium. To keep your terrarium plants neat and tidy, trim them when they become overgrown and have crowded the terrarium. You can also prune their roots to keep them small.

Failure to Remove Dying Plants

If a terrarium plant looks like it might be diseased, dying, or not thriving, remove it immediately because its problems can infect other plants. Use a small shovel, terrarium tool, chopsticks, or long spoon to remove the plant, being careful not to disturb the roots of other plants. Replace the plant with one of a similar size and the same moisture and light requirements. Be sure to surround the roots with soil, leaving no air pockets.

Dirty Glass

Every once in a while, clean the glass of your terrarium inside and out. If the glass is too dirty or foggy, it will be difficult for light to reach your plants. Use a damp piece of newsprint or a lint-free cloth. Do not use harsh cleaning products inside the terrarium because the chemicals in the cleaning products could harm your plants.

Over Watering

One way to prevent over-watering is to use a spray bottle instead of a watering can. If you do over-water, absorb any extra water with a paper towel. Leave the top off of your terrarium until it has dried out. If using mosses in your terrarium, you might want to lean towards a closed terrarium system since these moisture-loving plants can survive well in a lidded terrarium and an enclosed rainforest-like environment.

Over Fertilizing

Most terrarium plants do not need to be fertilized. You want to keep terrarium plants small and inhibit their growth, so don't feed them because the plants will quickly outgrow their confined space.

Choosing the Wrong Plants

While it's possible to grow almost anything in a terrarium, selecting plants that will thrive in the type of terrarium you are creating is essential. If you're designing a closed terrarium, select plants that prefer a moist environment. Also, make sure to combine plants with the exact light requirements. Low-light plants generally work best.

Planting Succulents in Closed Terrariums

Succulents generally thrive in high light and low moisture environments. If you plant succulents in a closed terrarium, the climate is too humid for them to succeed. You can solve this dilemma by creating and planting succulents in an uncovered, open-dish garden. Note that even a large jar will be too humid—airflow is essential, and air must be able to circulate around succulents.