How Often Should You Water Closed Terrarium Plants

Water, light, and heat, are the basic moving pieces of maintaining a healthy and blooming terrarium. And while all are fairly simple to get right for more experienced terrarium builders, everyone started with the exact same google searches looking for the right answers. One of the main ones is, how often should you water your terrarium plants.

Water your terrarium plants no more than once every three months, a little at a time. Closed terrariums need very little to no watering after you set them up. There should already be enough moisture inside. Overwatering can ruin your plants, as the water has nowhere to go once you seal the terrarium. Less is more.

But how do you know how much water’s enough to begin with? What are the signs of too much water, or too little water? How to be sure that you won’t overwater or dehydrate your plants???

How Often To Water Closed Terrarium Plants?

Closed terrariums are very delicate when it comes to watering, as once you close them no moisture can come in, and go out.

Too little water = your plants shrivel up and die

Too much water = your plants’ rot, mold takes over your beautiful jarred garden

Generally speaking, most beginners go down the pitfall of overwatering and drown their starting terrariums.

With normal plants, you keep in pots the water can drain out, and eventually evaporate. Terrariums use the same water over and over again in many cycles, so it must be limited to just the right amount.

This amount depends on many factors:

  • terrarium size
  • plants used
  • amount of soil
  • amount of plants

A general rule of thumb is to use:

  • ¼ cup for a quart-sized terrarium
  • ½ cup for a half-gallon sized terrarium
  • 1 whole cup for a gallon sized terrarium

Always Use A Spray Bottle

When watering your terrarium plants always use a spray bottle to spray the water onto the walls of your terrarium, and never pour the water in directly.

The idea is to spray the walls inside the terrarium and make sure the water is sliding down the walls and into the soil.

Spray in a circular motion and evenly cover all of the glass sides.

How To Know If I’ve Put In Enough Water?

After watering your terrarium check the soil. It should be moist to the touch, but not soaked. If you soak the roots in too much water and prevent them from circulating air, your plants will develop a fungal infection called root rot.

The roots will become brown, soft, and well, rotten!

Fortunately, this can be prevented by adding a bottom drainage layer when building a terrarium.

How To Tell If I’ve Put in Too Much Water?

The best way to tell if you’ve put in too much water is by touching the soil and checking if it’s slightly wet, or soggy and soaked.

Another way to tell is by looking for condensation. Though there will always be some level of condensation.


Watering your terrarium plants can be a headache and is definitely more of an art than a science. There are so many factors in play, and the best thing you can do is not overthink it and add water a little at a time.

If everything looks ok and the soil is just right to the touch, seal it up and let it be! The last thing you want to be doing is opening it up compulsively to check the moisture.

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