Common problems with terrariums and how to prevent them

Common problems with terrariums and how to prevent them

As closely as we follow instructions when creating our terrarium and looking after it, sometimes problems do happen. They're usually nothing to worry about and can be prevented or treated with some key things. Read on to find out about some of the common problems with terrarium making and how to solve them.



Mould and fungus, which usually present as white and little fuzzy, thrive in dark, damp conditions. In a closed terrarium this is therefore a common problem. It is less of a problem in open terrariums but it is still possible, especially if you are overwatering. Succulents don't like their leaves getting wet so make sure to water the soil directly. Here are some tips on how to prevent or treat mould and fungus issues in your terrarium.

  1. Prevention is better than cure, so make sure before planting your terrarium you have thoroughly cleaned your glassware, and made sure your substrates are clean.

  2. Use the right soil or compost that drains well and doesn't retain too much moisture. Did you know you can bake soil in the oven to kill any harmful organisms? We use coconut coir (with added plant nutrients) as part of our kits which is usually much less prone to mould or fungus development.

  3. Add activated carbon to your terrarium. I sometimes mix some of the carbon in directly with the soil which can also help.

  4. Place your terrarium in a spot that is well-lit and where it is receiving indirect sunlight. To prevent mould, ensure that your terrarium is not in the dark.

  5. Remove mouldy bits as soon as you can before treatment, using long tweezers or chopsticks.

  6. Adding springtails to your ecosystem can also help. Springtails feed on decaying organic matter as well as mould and fungus and will excrete healthy nutrients back into the soil which acts as fertiliser. You can do this both as a prevention and a cure. Make sure not to mix neem oil (or other insecticide) with springtails as the neem oil will kill them.

  7. Open your terrarium once a week for a few hours every now and again to allow air to circulate. You can spray some neem oil over your plants and soil while it is open. The best mix is a teaspoon of neem oil to a litre of water and a drop of soap to help blend it together. You can buy neem oil ready mixed or pure oil if you'd like to make your own mix right here. Do this once a month or every two weeks until the problem goes away. A little goes a long way so don't saturate your plants with this mix.



Pale leaves

This is usually a sign that your plants are not getting enough light. If they are otherwise in good condition (not too dry or too wet) then you can place it somewhere that is getting a little more light.

If your leaves are yellow, however, this is usually a sign of too much sun. Take it out of the light and place it somewhere that is getting a bit less light.


Shrivelled Leaves

Leaves can be shrivelled either because they are too dry or too wet. If the plant is dry or crunchy to the touch, then it is likely it is already too late. If you notice them looking a little droopy, it is usually time for some more water to avoid this happening.


Insects and critters

Most of the time, insects and critters are not much to worry about. If you notice little white, slightly longer in the body insects crawling around quickly they are most likely springtails. Leave them in there! They are wonderful for terrarium health. Similarly, if you see tiny, black, round insects that move slowly, they can also be left in. They are called soil mites and behave similarly to springtails by feeding on dead or decaying plant matter.

If you see little flying creatures they are likely to be fungus gnats. They can be harmful to plants. We recommend opening your terrarium and treating it to a neem oil spray. The eggs lay dormant in the surface layers of the soil and prefer a humid environment so it is difficult to treat this without harming your terrarium by drying it out. If you bake your soil beforehand then you can prevent this from happening in the first place as any eggs or flies will be killed before you plant your terrarium.

You may also introduce nematodes to your terrarium, which are also little critters that feed on fungus gnats and other species that can be harmful to your terrarium.

Another option is to introduce sticky fly traps either inside the terrarium or if you open the terrarium and leave the fly traps outside it. 

Finally, you might also want to introduce a carnivorous plant to your terrarium which feed on insects. Carnivorous plants work well in a closed terrarium as they enjoy the humid environment - their natural environment tends to be dark swamps!