10 Care Tips for your Closed Terrarium Plants

Closed terrariums have become increasingly popular among plant enthusiasts due to their self-sustaining and low-maintenance nature. 

These miniature ecosystems, enclosed in glass containers, create a perfect environment for plants to thrive with minimal intervention. 

However, like any other living organism, plants in closed terrariums require specific care to ensure their health and longevity. 

In this blog post, we'll explore 10 essential care tips to help you maintain a flourishing closed terrarium.

1. Choose the Right Plants

Selecting the appropriate plants for your closed terrarium is crucial for its success. 

Opt for plants that thrive in humid environments and have similar light and water requirements. 

Common choices include ferns, mosses, and small tropical plants like fittonias and nerve plants.

When choosing plants, consider their growth habits and ensure they won't outgrow the terrarium space quickly. 

This thoughtful selection will help maintain a balanced and visually appealing terrarium over time.

2. Mindful Watering

Watering is a critical aspect of closed terrarium care. The closed environment creates a self-sustaining water cycle, but it's essential to strike the right balance. 

Overwatering can lead to fungal growth and root rot, while underwatering can cause the ecosystem to dry out.

Monitor the moisture levels by observing condensation on the glass. If it's consistently foggy, reduce watering, and if it's too clear, add a bit more water. 

Use a spray bottle for controlled and even watering, focusing on the soil rather than directly on the plants.

3. Proper Light Exposure

Closed terrariums thrive in indirect light, simulating the dappled sunlight found on the forest floor. 

Place your terrarium in a location with filtered or indirect sunlight, avoiding direct exposure to avoid overheating and damage to the enclosed plants.

Rotate the terrarium occasionally to ensure all plants receive an equal amount of light. 

If natural light is insufficient, consider supplementing with artificial light sources, such as LED grow lights, to maintain optimal plant health.

4. Pruning and Trimming

Regular pruning and trimming are essential to control the size and shape of plants within the closed terrarium. 

Remove any yellow or dead leaves promptly to prevent the spread of disease and maintain the aesthetic appeal of the terrarium.

Pay attention to the growth patterns of each plant, and trim accordingly to prevent overcrowding. 

Trimming also allows for better air circulation, reducing the risk of mold and maintaining a healthy environment for your plants.

5. Maintain Adequate Ventilation

While closed terrariums are designed to be sealed, some ventilation is necessary to prevent the buildup of excess moisture. 

Periodically open the lid to allow fresh air circulation, especially if you notice persistent condensation or detect a musty odor.

Be mindful not to leave the terrarium open for extended periods, as it may disrupt the delicate balance of the enclosed ecosystem. 

Aim for short, periodic openings to refresh the air without compromising the humidity levels.

6. Fertilize Sparingly

Closed terrariums generally require less fertilization than traditional houseplants. 

The enclosed environment provides a recycling system where decomposing organic matter releases nutrients into the soil. 

However, if you notice signs of nutrient deficiency, such as pale leaves or stunted growth, consider using a diluted, balanced liquid fertilizer.

Apply the fertilizer sparingly, following the recommended dosage, to avoid overfeeding and disrupting the delicate balance of the terrarium ecosystem.

7. Monitor and Control Pests

While closed terrariums are less susceptible to pests compared to open environments, occasional pest issues may still arise. 

Keep an eye out for signs of pests such as small insects or webs on the plants.

If pests are detected, address the issue promptly by removing affected leaves or using natural remedies like neem oil or insecticidal soap. 

Quarantine the terrarium if necessary to prevent the infestation from spreading to other plants.

8. Choose the Right Soil Mix

The soil composition in a closed terrarium is critical for plant health. Use a well-draining and nutrient-rich soil mix tailored to the needs of your selected plants. 

A mix of peat moss, perlite, and orchid bark works well for many closed terrarium species.

Avoid using garden soil or heavy potting mixes, as they can lead to poor drainage and hinder the proper functioning of the closed ecosystem.

9. Regularly Inspect and Clean the Glass

Maintaining a clear view into your closed terrarium is not just for aesthetics; it's also essential for the health of the plants. 

Over time, dust and mineral deposits can accumulate on the glass, reducing the amount of light that reaches the plants.

Regularly inspect the terrarium and clean the glass with a soft cloth or sponge to ensure optimal light penetration and visibility. 

This simple task can significantly improve the overall health and appearance of your closed terrarium.

10. Be Patient and Observant

Finally, patience and observation are key to successful closed terrarium care. 

These miniature ecosystems take time to establish and reach a balanced state. 

Resist the urge to make frequent changes or interventions, allowing the plants to adapt and grow at their own pace.

Regularly observe the plants, soil, and overall condition of the terrarium. 

This attentiveness will enable you to identify and address issues early, ensuring a thriving and sustainable closed terrarium environment.

​Final Thoughts 

Closed terrariums offer a captivating and low-maintenance way to bring nature indoors. 

By following these 10 care tips, you can create an optimal environment for your plants to flourish while enjoying the beauty of a self-contained ecosystem.

Frequently Asked Questions (FAQs)

Can I use any glass container for a closed terrarium?

It's best to use containers with a tight seal, such as jars or aquariums with lids. This helps create a closed environment that retains moisture and promotes a self-sustaining ecosystem.

How often should I water my closed terrarium?

Monitor the condensation on the glass. If it's consistently foggy, reduce watering; if it's too clear, add a bit more water. Typically, watering every 2-4 weeks is sufficient, but adjust based on the specific needs of your plants.

What do I do if my closed terrarium has a bad smell?

A musty odor may indicate poor ventilation. Open the lid briefly to allow fresh air circulation. If the smell persists, check for signs of overwatering or decaying plant matter and address the issue accordingly.

Can I use tap water for my closed terrarium?

Using distilled or rainwater is preferable to tap water, as it avoids introducing minerals and chemicals that may disrupt the terrarium's delicate balance. If tap water is your only option, let it sit for 24 hours to allow chlorine to dissipate.

Is direct sunlight harmful to closed terrarium plants?

Yes, direct sunlight can lead to overheating and damage within a closed terrarium. Place your terrarium in a location with filtered or indirect sunlight to ensure optimal conditions for plant growth.

How do I know if my closed terrarium needs fertilizing?

If you notice signs of nutrient deficiency, such as pale leaves or stunted growth, consider using a diluted, balanced liquid fertilizer. However, it's generally best to fertilize sparingly, as closed terrariums have a self-sustaining nutrient cycle

What should I do if my closed terrarium plants are growing too rapidly?

If your plants are outgrowing the terrarium quickly, consider pruning and trimming them regularly to maintain a balanced and visually appealing environment. You may also need to adjust the frequency of watering and monitor the overall health of the plants to prevent overcrowding.

Can I create a closed terrarium with succulents or cacti?

Closed terrariums are not suitable for succulents and cacti, as these plants prefer arid conditions and well-draining soil. Closed terrariums, with their high humidity levels, can lead to root rot and other issues for these types of plants. It's better to choose plants that thrive in humid environments for closed terrariums.

How do I deal with mold in my closed terrarium?

Mold can develop in closed terrariums if there is excessive moisture or poor ventilation. To address this issue, open the terrarium for a short period to allow fresh air circulation. Remove any affected plant material and adjust the watering frequency to prevent future mold growth. If the problem persists, you may need to replace the soil with a well-draining mix.