Watering terrariums is a tricky topic and is often the difference between their life and death. Being in a sealed container, the water has nowhere to run off to so it is vital not to overwater. I only ever mist terrariums and NEVER use a watering can/bottle, the aim is to keep the substrate slightly moist but never wet. If in doubt, less is always best!
As a general rule of thumb, the substrate should feel like a sponge that has been rung of all its water; as if you were about to wipe a dusty surface. Of course, plants have different requirements but you’ll have to use your judgment there.
I highly recommend using distilled, deionised or reverse osmosis water for your terrariums. Distilled water can be purchased online and deionised water can be bought from any supermarket’s car section. Reverse osmosis water can be bought from your local aquatics store (I get mine from Maidenhead Aquatics and it’s around £5 for a huge container).
If the above isn’t possible then I recommend using Brita filtered water or bottled water. You shouldn’t be watering your terrariums often so it’ll last a long time.
Tap water contains chemicals and minerals that build up in the soil and stain the glass. Avoid using it.
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.
I highly recommend using grow lights and not natural light. This is simply because grow lights are far easier to control and enable you to position your terrarium anywhere in your home. Relying on natural light is unreliable and can quickly result in the demise of your terrarium if it is left in the sun for even a short period of time. If you still want to use natural light then place it in a north facing window.
I use warm white LED lights for my plants – https://amzn.to/2Zs6lcD (please note that this is an affiliate link and I will receive a small commission with any purchases)
I also use IKEA VAXER Cultivation bulbs that fit into an E27 fitting – https://www.ikea.com/gb/en/p/vaexer-led-bulb-for-cultivation-par30-e27-60317483/
I’m no expert on light spectrums for plant growth so I’ll point you in the direction of Darryl Cheng, author of the New Plant Parent. The best houseplant book ever written, in my opinion –
Springtails, isopods and microfauna
A terrarium mimics a tropical environment in a closed glass container. Unfortunately, mould and unwanted bacteria also thrive in these conditions and the way to combat it is to introduce springtails and other microfauna to your terrarium.
Springtails (Collembola) are tiny Hexapods that feed on mould, fungi and decaying matter. Around the size of this fullstop (.) a single springtail won’t dent a mould breakout but in large numbers, they can bring it to a screeching halt. For more information on Springtails, isopods and other microfauna, I’ll point you in the direction of my friend Adam who runs the business ‘Micro Excotics’ (www.microexotics.co.uk)
It is worth noting that not all mould is going to results in the death of your terrarium. If you have a healthy colony of springtails and a decent amount of airflow then mould outbreaks will be quickly taken care of.
All plants grow at different speeds so naturally, some will need more frequent pruning than others. By knowing exactly what plant you have, you can make an educated decision on how to approach pruning. 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!
It’s hard to give a blanket explanation but here are a few pointers.
- Try not to let leaves sit against the glass as they can rot when condensation forms.
- Prune close to a node or the stub left can rot
- Identify the plant you are pruning
- Allow the plants to grow and don’t prune too quickly or heavily; plants need to grow to develop and maintain vigor.
See the below image for correct pruning technique.
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.