Care

Watering

Watering terrariums is a tricky topic and is often the difference between their life and death. Being in a sealed container the water cannot evaporate so it is vitally important not to overwater, I only ever mist terrariums and NEVER use a watering can/bottle; the aim is to keep the substrate moist but not wet. The substrate I use is well draining and is separated from the drainage layer with membrane and charcoal layer. This helps the soil drain and ensures it is not sat in water which keeps it sodden.

I like to give the analogy that the substrate should look/feel like a sponge which has been rung of all its water; as if you were about to wipe a table

Light

Lighting is one of the most important aspects of plant growth; without it, they simply cannot survive. It is one of the most misunderstood topics and I believe that it is the second most common reason for houseplant death, with watering being the first.

A good rule of thumb is to let the terrarium sit in a position where it will see as much of the sky as possible but without sitting in the sun. A north facing window is perfect. If this isn’t possible then additional grow lights will be needed. LED bulbs are cost effective and can be used in standard lamps but be sure they are suitable for plant growth as standard bulbs do not give the plants the right spectrum of light for plants to photosynthesize. CFL (fluorescent) bulbs are also a cost effective option and are widely available. Reptile shops sell higher quality grow lights specifically designed for plant growth and while they are more expensive, they produce better quality light.

The problem a terrarium poses is that it is a glass container, usually with a small opening, so if it sits in the sun for a prolonged period it will act as a greenhouse and will quickly reach undesirable temperatures. If left at these temperatures, the plants inside will be harmed and can die so it is important not to let the terrarium sit in the sun.

Pruning

All plants grow at different speeds so naturally, some will need more frequent pruning than others. It is hard to give a blanket explanation for pruning plants in a terrarium as there can be many inside a single one so it is best to familiarise yourself with basic pruning techniques and to keep an eye on how the plants are growing. Another important part of pruning is to understand how the plant you are pruning grows. By knowing exactly what plant you have, you can make an educated decision on how to approach pruning (and other aspects). While learning Latin names can seem daunting at first, it eliminates any ambiguity regarding plant identification. It would be incredibly frustrating if you too eagerly pruned your Ficus quercifolia (a slow growing Ficus) thinking it was the fast growing Ficus pumila, you’d have to wait an eternity for it to grow back!

I said it’s hard to give a blanket explanation but here are a few pointers.

  1. Try not to let leaves sit against the glass as they can rot when condensation forms.
  2. Prune close to a node or the stub left can rot
  3. Identify the plant you are pruning
  4. Allow the plants to grow and don’t prune to quickly or heavily; plants need to grow to develop and maintain vigor.

See the below image for correct pruning technique.

Image from Virginia Cooperative Extension

While I have listed a few important topics here I certainly haven’t covered everything. If you have any issues you need help with don’t hesitate to get in touch.