People often say that terrariums are low maintenance and simple to take care of. After a few months, when things start to go wrong, it can be disappointing. Perhaps the glass has become fogged with green algae. Or a fern’s once-tidy leaves have become wild and could push the lid up. Sometimes the worst thing that can be found is a pile of brown, rotting mush where a plant used to grow.
There are a lot of resources on how to build and design terrariums, but not as many on how to fix terrariums that are dying. Even if you plant your terrarium with great care, it will probably need some work every 6 to 12 months. Container size plays a role too. Botanist James Wong recently said that a terrarium that is at least 12 inches by 12 inches is much more likely to give plants a stable, long-term environment. Though you can keep plants in smaller pots, don’t count on them to keep their original look over time.
The good news is that a sick terrarium can often be brought back to health with some detective work and love. This step-by-step guide will help you get your plants back on track and bring the mini ecosystem back into balance.
Diagnose the Problem
Carefully observe the terrarium to identify any issues. Are plants dying or turning a weird color? Does the soil look very dry or muddy? Is there green slime on the glass? Does something smell bad? Figuring out what the problems are is important before you do anything. The most common things that kill terrarium plants are not enough water, too much light or heat, and not enough air flow.
Fix Watering Problems
Too much or too little water causes more terrarium deaths than anything, Plants wilting despite wet soil indicates overwatering, Allow more ventilation to lower humidity, Remove soaked moss and replace with dry sphagnum moss to absorb extra moisture,
If plants are shriveling and soil is dusty, give small drinks with a pipette or spray bottle right to the base of plants. Mist moss layers lightly. Increase watering frequency while closely monitoring soil moisture.
Adjust Light and Temperature
Plants turning brown or lanky often results from too much light or heat Move the terrarium away from sunny windows and use sheer curtains to filter light Moderate temps with air conditioning or fans,
If plants seem small and compact they likely need more sunlight. Gradually relocate the terrarium to brighter spaces watching for signs of stress. Rotate it so all sides get even light.
Increase Air Circulation
Stale air and high humidity breed mold, algae and fungal diseases. Prop open the lid with a stick for a few hours daily to improve airflow. Add a small battery-powered fan to gently circulate the air. Just don’t leave the lid open too long or plants may wilt.
Prune Overgrown Plants
It’s easy for terrarium plants to become overgrown. Carefully trim back any plants touching glass or overwhelming their neighbors. Cuttings can be propagated in potting mix for later replanting. Pruning increases air flow and light penetration.
Clean the Glass
Wipe down the interior glass with paper towels and mild cleaners like diluted vinegar. Use a soft cloth to gently remove stubborn algae buildup. Completely rinse and dry the glass before replacing plants. Regular cleaning prevents future scum issues.
Remove Dead Material
Eliminate any rotting plant matter, dead leaves and contaminated soil. Clip away dead roots and scrub plant containers to destroy mold spores. Replace any decaying moss. This removes disease sources and gives plants a fresh start.
Consider Replanting
If many plants have died or the terrarium is beyond saving, a complete replant may be needed. Wash the container in hot soapy water. Use fresh potting mix and rinsed pebbles/gravel for drainage. Choose plants suited to the new lighting and humidity levels. Adjust care routines to prevent future problems.
With attentive troubleshooting and care, even severely neglected terrariums can bounce back. Be patient and allow plants adequate time to recover between adjustments. A revived terrarium may not match the original, but with trial and error it can thrive again. Don’t let problems progress too far before taking action – catching issues early makes salvaging dying terrariums much easier.
Choosing the Right Plants and Materials
Prevention is better than a cure. Picking appropriate plants and materials from the start significantly reduces problems later on.
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Select plants suited for terrarium conditions – consider humidity, light needs, growth rate. Popular choices include ferns, mosses, small tropical plants.
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Use quality terrarium soil mix – well-draining and specifically formulated to prevent overwatering and root rot.
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Include drainage layer – pebbles or gravel at the bottom improve drainage and keep water from pooling around roots.
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Consider activated charcoal – helps filter impurities and reduce odors.
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Maintain cleanliness – regularly remove dead leaves and debris to prevent harmful bacteria/fungus buildup.
Pro Tip: Understand Closed vs. Open Terrariums
The terrarium type – closed or open – greatly impacts care.
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Closed terrariums create a self-sustaining humid ecosystem. Need less frequent watering but more prone to overwatering and fungal problems.
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Open terrariums have better ventilation, suitable for plants preferring drier conditions like succulents. Require more frequent watering.
Troubleshooting Questions
How do I know if my terrarium is overwatered?
Signs include yellowing leaves, mushy stems, standing water, mold growth, foul odors, and constantly soggy soil.
How often should I water the terrarium?
Closed terrariums – Every few months.
Open terrariums – Weekly or when soil is dry.
What kind of water is best?
Use distilled water to prevent mineral buildup in soil over time.
Why is my terrarium getting moldy?
Excessive moisture and poor ventilation cause mold. Improve airflow by opening more or adding ventilation holes.
Can I use regular potting soil in a terrarium?
No. Terrariums need well-draining mixes specifically formulated to prevent root rot.
What are the best terrarium plants?
Closed terrariums – Ferns, mosses, small tropical plants.
Open terrariums – Succulents, cacti.
How much light does a terrarium need?
Indirect or filtered light. Avoid direct sun which can scorch leaves.
Reviving a Dying Terrarium Takes Patience and Persistence
Bringing a dying terrarium back to life requires careful observation, diagnosis, and action. Understanding your plants’ needs and providing the proper conditions transforms a struggling ecosystem into a thriving world in miniature. Remember to be patient and persistent, and don’t be afraid to experiment until you find the perfect balance. Pay close attention to avoid problems progressing too far. Your attention and care can make the difference between terrarium life and death.
The Glass is Dirty
If your glass is green, it’s a sign that algae has started setting up home. If you have a large tank-style aquarium with flat sides, you can use an aquarium scraper or even an old credit card to remove algae easily. On curved glass, paper towels or a clean rag are perfect. White streaks are usually caused by mineral deposits caused by watering with tap water; if you can, use rainwater or distilled water to fix the problem. You may be able to wipe away the streaks with a cloth dampened with lemon juice or vinegar (keep this well away from your plants). Then follow up with a cloth dipped in rainwater or distilled water. If that doesn’t work, you’ll have to take the terrarium apart, clean the glass with vinegar, rinse, and put it back together again.
The Plants Are Leaning to One Side
Your specimens are probably trying to grow towards the light source. Turn your terrarium slightly every few days so that the plants all get the same exposure to light, and if they get leggy, move the terrarium to a brighter spot, still out of direct sunlight.
THIS is KILLING Your Terrariums!
FAQ
How do I bring my terrarium back to life?
To check if the soil and moss are dry, open the lid and feel them. If they feel dry, give the terrarium a light spray of water. Be careful not to overwater it; it only needs a little. Then put your lid back on and monitor over next few days.
How to fix a dying terrarium?
Keep your terrarium in a stable environment, away from extreme heat or cold. Terrariums are beautiful, rewarding projects, but they do require some attention to thrive. If yours keeps dying, it’s usually a simple fix—just tweak your watering, check your plant choices, and make sure the setup is right.
How do you revive an open terrarium?
There are several troubleshooting steps you can take to revive it. First, check for signs of overwatering or underwatering and adjust your watering routine accordingly. Examine the light conditions and ensure your terrarium is receiving the appropriate amount of light for the plants inside.
What is the lifespan of a terrarium?
Terrarium Lifespan Though, the average terrarium lasts only about 4 months to 2 years. Perfect conditions are not easy to provide, in fact, they’re almost impossible. And such a terrarium only exists on paper. Bummer right?.
Why are terrariums dying?
Some of the main reasons terrariums die are giving the plants or soil too much water, using the wrong containers, mixing plants that need different amounts of water, and putting the terrariums in the wrong places. Overwatering plants in the terrarium is one of the most common mistakes and reasons why terrariums start dying.
Can terrarium plants die?
While terrarium plants can die, it is not a common occurrence. There are a number of reasons why a terrarium plant might die, including: too much or too little water, too much or too little light, and improper care. However, if a terrarium plant does die, it is typically because of one of these three reasons.
Can a terrarium get too long?
Yes, if your plants in a terrarium get too long, there’s a higher risk of them dying. That’s because tall plants will touch the terrarium’s sides and soak up water, which can kill the plants. If your plants get too long or big, make sure to prune them a little. It’s always a good idea to choose slower growing plants for a terrarium.
How do you care for a terrarium plant?
Solve by placing the terrarium in a bright but indirect light. Leaning to one side means that you need to turn your terrarium once a week or so to allow all parts of a terrarium to get enough sunlight. You can read a terrarium plant pruning guide here. Avoid fertilizing plants too much as it will lead to faster growth.
How do you design a terrarium?
Lay out the plants on the soil to get a feel for the design. Place taller plants at the back of the terrarium and shorter ones at the front. Choose complementary foliage textures and colors. If all of the plants have variegated broad leaves it will look like just one large plant. Remove the plants from the nursery pots and plant them in the soil.
Can you put plants in a closed terrarium?
Even though they like wet soil, they need high heat – which you can’t provide in closed terrarium. If direct light hits the terrarium, it will cook the plants inside. The best suited plants for closed terrariums are mosses, lichen, ferns, some tropical plants. You can find a list of plants for closed and open terrariums here.