We’ve been given a large terrarium – how do I set it up?

(Question)

A large terrarium has been donated to the Broadview Housing Gardening Committee.  Any references, books in particular that you can provide on what soil to use and what plants are nest suited to terrariums would be appreciated.

 

(Answer)

Terrariums are a great way to grow and showcase many plants with minimal care once properly planted and located.  I’ve identified a number of references for you below.  With respect to your specific questions on soil and plant selection:

  • The growing medium should take up about a quarter of the volume of your container.  Start with a layer of small stones, decorative rocks or other drainage material.  Top this layer with a ½ inch of activated charcoal (available in aquarium supply stores).  The activated charcoal acts as a filter for closed terrariums and neutralizes the odours from decaying matter. Top this with a good quality sterilized potting soil.  A layer of sphagnum moss placed over the charcoal will help keep the potting soil from sifting down into the drainage area.
  • Many plants can be effectively grown in a terrarium.  In general, plants with a low, dense growth habit are best suited.  Before making your plants choices, determine the location for your terrarium so you know the available light and temperature when making your plant selections.  The article referenced below contains lists of terrarium suitable plants along with their height and light and temperature requirements.

Terrariums, University of Missouri Extension

https://extension.missouri.edu/p/g6520

Two books on terrariums available in the Weston Family Library at the Toronto Botanical Garden are:

Miniature Gardens, Katie Elzer-Peters, 2014

Making and Using Terrariums and Planters, Allen Daley, 1986

Non-members are not able to borrow books from the Toronto Botanical Garden library but you are welcome to visit and make use of the books there. The library is open 10:00-4:00 daily.  I confirmed that both of the books are also available from the Toronto Public Library.