Working out how much water to put in a closed terrarium is tricky, especially when you’re a new terrarium plant parent. Obviously, when you get new plants the first thing you do to look after them after finding them a nice place to live is to water them. But did you know that closed terrariums don’t actually need watering that much, if at all.
You want to give your closed terrarium the best environment to thrive in, but by opening it up and watering it you can actually damage its fragile ecosystem and disrupt the water cycle. That’s right closed terrariums have their own water cycle.
If you’re worried your terrarium has had too much to drink and over watering has happened, our checklist of signs will help you to check your closed terrarium and find some solutions to restore the balance. But before you do, if you’re looking for how often to water your closed terrarium head here to find out more.
Excessive Condensation on Glass
What to look for: Look for heavy water droplets or fogging that persists all day across large areas of your closed terrarium. Some is a good sign the water cycle is working but if there’s a lot running down your glass it’s a sign your terrarium might be too wet. Your humidity level inside is too high.
Solution: Check the soil to see if it is wet and leave the lid open until the condensation reduces. This will help to allow excess moisture to escape. But remember, you don’t want it all to escape, because a closed terrarium relies on having a working water cycle.
Soil looks wet
Sign: Soil looks darker and more dense than usual. You can’t really notice any air pockets. If you notice any signs of water on the op of the soil you have definitely over watered your closed terrarium.
Solution: Remove any excess water by carefully soaking it up with a paper towel, then add more dry substrate (e.g., coco coir or sand) to absorb the moisture.
Mould Growth
Sign: Fuzzy white fur, Saprophytic Fungus, is the most common type of mould or fungus that grows inside a closed terrarium. It looks so delicate like a soft, cotton-like white fuzz. Often found growing on the soil surface, plant leaves, or even on decorative items like rocks or wood.
Solution: It’s usually found in decaying material that has a higher than usual level of humidity. It is generally harmless to plants, but it is still best to remove the mouldy parts of plants, soil, or your decorations. Let the terrarium air out and change your watering schedule. Also consider repositioning your terrarium somewhere with more light.
Fungal Growth on Plants
Sign: Botrytis mould, or more commonly grey mould, appears as grey or brown fuzzy patches on plant leaves, stems, or flowers. It often starts as small water-soaked spots that later turn into soft, mushy areas. Botrytis can lead to leaf decay, and in severe cases, it may spread rapidly, causing major damage to your plants.
Solution: Remove infected leaves or plant parts immediately to prevent the fungus from spreading. It spreads pretty quickly in a warm moist environment where leaves don’t dry out and it spreads from touch, so if your terrarium is overcrowded it spreads even faster.
Improve your terrarium’s air circulation by opening the terrarium, and you’ll need to do this every day while you dry it out. Avoid overwatering and consider investing in a … to measure humidity in your closed terrarium.
Leaf Blisters or Oedema
Sign: Small, raised, water-filled blisters or bumps appear on leaves. This happens when plants take in more water than they can use, and it erupts out on their leaves as a way of getting rid of the moisture. It’s common in closed terrariums when there is too much humidity and poor air flow.
Wilting Plants Even When Soil’s Wet
Sign: Oddly overwatered plants can wilt or look droopy as if they don’t have enough water even though the soil is wet. It’s a sign of overwatering. This is because overwatering can suffocate the roots by cutting off oxygen, leading to root damage.
Solution: Stop watering your terrarium as frequently and open the lid to let the terrarium air out. If you notice a smell, your problem could be more serious, so have a good look at the plants and decorations in your terrarium for other signs of overwatering.
Soft, Mushy Leaves or Stems
Sign: If you see leaves and stems looking soft, mushy, or discolored turning brown or even black it’s a sign of root rot setting in because of excess moisture. Sadly at this point, you often can’t save your plant. Plants in closed terrariums are more prone to developing soft, mushy leaves because of the high humidity, especially plants that prefer drier conditions.
Yellowing or Dropping Leaves
Sign: Leaves may turn yellow or even drop off the plant if they are being overwatered. If you notice yellowing occurring at the tips, check your terrarium. The sooner you catch the signs of over watering the more likely you are to save your plants and rebalance the ecosystem of your closed terrarium.
Solution: Reduce watering frequency immediately and ensure excess moisture can escape by opening the lid to ventilating the terrarium so the humidity level drops.
Algae Growth
Sign: Green or brown algae forming on the soil, decorations, or glass walls.
Solution: One way to get rid of algae, if it is only on the glass is to use a touch of vinegar mixed with water (1 part vinegar to 3 parts water) to clean the glass. If it is on your plants, try reducing sunlight or consider pruning your plant depending on amounts. Opening the terrarium for some fresh air can also lower humidity and help prevent further algae growth. Also consider moving your terrarium as sunlight encourages algae growth.
Mushrooms or Fungi Appearing
Sign: Small mushrooms or fungal growths start emerging from your soil or wood pieces. The mushrooms are not likely to harm your plants, depending on what you have in your closed terrarium, but they are a definite sign that your moisture levels are too high. It’s also telling you that you have too much organic material decomposing, from leaves dropping etc, so you need to do some work on your terrarium.
Solution: Remove the mushrooms and surrounding soil if it feels very wet. Replace this with new soil and reduce the number of times you water your terrarium. Also consider opening it up to remove any falling leaves or plants that seem unhealthy. Let your closed terrarium air for a while before sealing it back up.
Standing Water at the Bottom
Sign: Visible water in the bottom of your drainage layer is a definitive sign that you have over watered your closed terrarium.
Solution: To save disturbing your garden use a pipette or turkey baster to remove the excess water immediately. Open the terrarium and let it air for at least a few hours. Consider opening it again in a few days if signs of excess moisture continue or you get a high humidity reading on your hygrometer. Change your watering schedule.
How much water should you put in a closed terrarium?
Now you know the overwatering signs to look for in your closed terrarium, you may be wondering how much water you should put in a closed terrarium. The answer is very little.
In a true closed terrarium, you should only water it when you plant it to begin the water cycle. The amount of water you use will depend on the size, the amount of soil and the number of plants. Remember less is more and if you see signs that your closed terrarium needs water, add a little more.
One of the best ways to know if your closed terrarium needs water is measure the humidity or moisture in the air. A small hygrometer will do this for you. Aim for 50-70% humidity for most closed terrarium plants.
Conclusion
Closed terrariums tend to show signs of overwatering through problems related to humidity control and mould related issues. Enjoy watching your mini-ecosystem thrive, but know the signs of over watering so you can act. The sooner you act, the more likely you are to save your closed terrarium from serious overwatering problems.
Remember, closed terrariums have an internal water cycle so do not need to be watered often. Always add water with a less is more approach to keep your closed terrarium happy and thriving.
