I have read many posts on building terrariums.  The majority of these posts recommend a drainage layer at the bottom of the terrarium.  In my experience, not only is a drainage layer unnecessary, it’s not healthy for the terrarium plants; overall health of the terrarium; and ends up looking rather unattractive and dirty.

There should never be so much water in your terrarium that it collects at the bottom.  As is the rule for potted plants, it is better to err on this side of under watering.  If water makes its way down to the drainage layer, the soil just above will be saturated and the water will eventually stagnate.  The excess water will also promote root rot and shallow roots in the terrarium plants.

The solution… use a well draining soil mix for your terrarium.  After planting your terrarium, water sparingly.  Watch your terrarium and add water as needed.

If you would like to include a layer or gravel for decorative purposes, you can cover it with a weed barrier or other horticultural fabric to prevent water and soil from draining into the decorative layer.

In the image above, a mound of moss is planted in a dish and placed on striped tiger stone.


  1. In my bottle gardens I always put a layer of aquarium gravel just in case it gets over watered (i water my bottles once a year). Then on top of the gravel is a shallow layer of activated charcoal to help be rid of mildew smells and then i put a layer of window screen to help hold the dirt up top where it belongs... This has worked great over the last 7 years on one of my bottles....

  2. Very, very Cool Terrariums!! The charcoal is 100% necessary and a great way to protect the roots. The screen is a great choice to keep the soil from going into the gravel layer.


All images and content copyright Jeffrey Schneider of JAMES Modern Terrariums 2009.