The simplest terrarium possible (do try it at home)

Materials for the simplest plant terrariums

Earth water cycle. By John Evans and Howard Periman, USGS (http://ga.water.usgs.gov/edu/watercycle.html) [Public domain], via Wikimedia Commons

I found out that simple plant terrariums can illustrate the water cycle. Cress in the terrarium evaporates water, which is condensed on the walls of the vessel. Then it falls to the bottom and is drawn by the cress roots again, imitating what happens to water in nature.

The plants are stable for weeks, unlike when growing cress on tissue paper.

The terrarium consists of several layers in a glass vessel. I used a bottle from dried herbs. From bottom to the top:

• Small stones or glass beads – the recipe used seed glass beads, which I didn’t have. I think cress in the vessel with pebbles looks healthier;
• some soil, I used potting compost;
• cress seeds scattered on top plus some extra soil.

I’d added a few mustard seeds after 4 days to make an  extra  level (smaller shoots). The roots are also visible near the glass wall, illustrating nicely how the plant grows.

Cress terrarium, 5 days

Cress terrarium, 8 days

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