Top 5 Questions about terrariums

We’ve compiled a list of the Top 5 questions we’re frequently asked about keeping a closed ('no-tech') terrarium, or bottle garden.


While it’s true closed terrariums are the ultimate low maintenance way of bringing nature indoors, they are living and breathing, so do take a small amount of care if you want them looking their best.

Don’t be afraid of rolling your sleeves up and getting your hands dirty with the odd maintenance session, it’s a great way of connecting with nature, and your mini eco-system will reward you with lush new growth and year round beauty. 

We also highly recommend investing in a good glass cleaning cloth, you’d be amazed at the difference giving your bottle a polish can do!


Answer: Little and infrequently

This advice is only relevant to ‘closed bottle terrariums’, as generally speaking, most of the terrariums we sell have lids or stoppers, and are powered by natural sunlight. The benefit of having a lid is it creates a nice humid environment for moisture-loving plants; in fact, it does this because a closed terrarium has all the right ingredients for it to have its own water cycle, thus creating a mini living breathing ecosystem in a jar!. 

Because closed terrariums recycle the water supply, they require very little regular watering. The frequency will depend on how big the vessel is, the species and number of plants inside, and light conditions. 

On average, our medium (20-30cm-ish) to large terrariums  (40-50cm-ish) usually need to be water once every two to three months -- a good healthy misting will do it (approx. 2-3 tablespoons).

Here are a few basic principles to figure out if you need to water your closed terrarium:

  • If your terrarium is regularly steaming up at regular times during the day (usually morning and evening), it has enough water.
  • If your terrarium is always steamed up, it may have too much water, or it may be too close to a heat source. If it is nowhere near a heat source, keep your terrarium up open for a few hours a day to let some of the excess moisture evaporate. 
  • If your terrarium never mists up, it may need more water.
  • If your plants look limp, or not as ‘perky’ as they usually do, your terrarium needs water.
  • If the soil or bun moss looks and feels dry, your terrarium definitely needs water.
  • Keep it away from direct heat sources and full sun. 

When you water your terrarium, we recommend using rain or distilled water. Using straight up tap water will eventually create a build up of unsightly, hard to remove calcium deposits. 

Invest in a mister or garden sprayer - gentle on foliage and helps clean the inside of your glass container. If you don’t have a mister, use the back of a spoon to trickle water down the side and give your terrarium a natural window clean.


Possible cause: You may have unsuitable or too many plants in your terrarium.

Terrariums have become available to buy everywhere you look these days, even at the supermarket checkout! Unfortunately, most of the ‘factory made’ terrariums you see around don’t stand a chance at survival because they contain plants that will quickly outgrow their container. Your terrarium might look gorgeous when you bring it home, but a few months later that Calatheas (‘Prayer Plant’) or Dracaena (Mother-in-laws tongue’) that looked so majestic at first, is cramped and the foliage is ‘bursting at the seams’. 

The other common mistake people make is using dry-loving plants in closed containers. I can’t tell you how many poor little succulents and cacti I’ve seen rotting away in jars with a cork. On the flip side, leafy moisture loving plants like ferns, peperomia and fittonia can look gorgeous when planted up in a bowl or open vase.

We only use species and size appropriate plants in our terrariums; humidity-loving species that stay small, and thankfully there are loads to choose from! Some of our favourites easy care plants include (many can be used in open terrariums too, but do your research first):

Small fern varieties (e.g. Button, rock, pteris and lace ferns) 

Most terrestrial and aquatic mosses


Jewel orchids

Small ivy varieties


Ficus ginseng bonsai

Tillandsia (airplants)


We personally don't use succulents and cacti much, nothing against them, apart from most of our projects are mostly inspired by lush leafy landscapes, where drought-loving plants wouldn’t thrive. 

Possible cause: Not enough drainage

The drainage layer in a terrarium is important to keep soil aerated, allowing roots to grow easily, and prevent root rot . We use Hydro clay pebbles at the bottom of most of our terrariums, whether open or closed. These little oven-baked orbs act as sponges, sucking up excess water and storing it for use in the water cycle, they also prevent the roots from sitting in water or dank sodden soil.  

Possible cause: Pests and diseases 

Occasionally, you may find hitchhikers have made their way into your terrarium. You may see slug trails, nibbles out of your plants, signs of plant decay (mould, slime, blackening leaves). Unfortunately, it's very difficult to remove pests and bugs once they are in your terrarium, so depending on the species, damage caused and population, you may find it easier to replant using. 

Some good news though for localised plant damage caused by decay - this can be isolated and removed without too much disruption, or even better by adding springtails and/or isopods as clean up crew to your terrarium. Springtails and isopods are little detritivores that love to eat dead organic matter along with fungi, mould, pollen, bacteria, algae and faeces. They also help keep the soil aerated by tunnelling to move around.

Lastly, If you’re foraging your own moss (legally and sustainably, of course), make sure you thoroughly rinse and quarantine your pickings before moving them in your container. Check out a great video from Serpa Design has a helpful video,  How to Propagate your own moss:



Answer: Yes, so long as your terrarium is not positioned by a heat source, and you don’t see any evidence of decay. Being permanently steamed up can signal overwatering, but it shouldn’t hurt your terrarium unless the soil is really sodden (which can promote and rot). If you don’t like it steaming up too much, or you think it may have been overwatering, take the lid off periodically to let some water evaporate.

Installing a good drainage layer made up of hydro clay pebbles will help absorb excess water, and allow roots to take it when needed .


Answer: Having leaves touching the glass is not a dealbreaker, but we do recommend trimming larger stem plants and ferns back occasionally to encourage new growth, and avoid foliage being in direct contact with condensation on the glass for long periods. 

As a basic rule --  trim any unhealthy, dry or brown foliage as soon as you notice it, this will keep your terrarium in good shape for years..  


Possible cause: Mould and fungus are very common due to the high humidity levels in a closed environment. Mould should be removed, and can be a sign of overcrowding, overwatering / rot, and disease.

Mould that appears on newly added wood is usually a sign the wood is still damp, in this case you can either a) remove the wood and wait for it to try out fully using a humidity meter, b) wipe away mould as it appears, the terrarium will eventually adapt and balance out again, or c) add spring tails and/or isopods.

The presence fungus/mushrooms and liverworts is nothing to worry about, unless you don’t like the look of them, in which case you can remove them.


Most importantly, take time to enjoy your terrarium 🌿


Ready Planted Terrariums for Store Collection, from £15.00

Terrarium plants and moss, from £3.99

Terrarium kits and supplies for home delivery, from £3.99

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1 comment

I purchased the HPotter Wardian upright on it own stand terrarium. Although it’s glass, it’s not sealed. How often should I water, as there is no condensation or visible base layers that can be seen. Thanks, bonnie crim

Bonnie Crim November 28, 2021

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