How to Care for a Demijohn Terrarium
Demijohn terrariums are beautiful, sculptural pieces that are often open or narrow-necked and can be trickier to access than a standard jar. That said, when set up right, they’re low maintenance and incredibly rewarding to grow.
This guide walks you through how to care for your demijohn terrarium and keep the balance just right. From moisture management to lighting and trimming, we’ve got you covered.
Demijohn terrariums need plenty of bright, indirect light to thrive. Place them near an east or west-facing window, or pull them back from direct sun if they’re facing south. A grow light can work too. Where you place your terrarium may change depending on the time of year. In the shop, we keep ours near a south-east window all year round.
Avoid direct sunlight
Too much sun can overheat the glass and scorch your plants. It’ll also throw off the humidity levels.
Avoid very low light
Low light slows plant growth and encourages mould. If the plants aren’t getting enough light, they can’t use up water, which can cause problems with moisture build-up.
As with any tropical-style terrarium, demijohns like a stable, warm environment. Keep them away from cold draughts, radiators, and anywhere that might drop below 13°C. A spot with consistent room temperature is ideal.
Once balanced, demijohn terrariums often don’t need much extra water. If you see a light mist on the glass that comes and goes with the weather, you’re probably spot on. Water very sparingly and only if things look noticeably dry.
Signs your terrarium might need water:
- Moss feels dry and crispy
- Soil looks pale and dusty
- Leaves develop brown tips or look bleached
Signs there’s too much water: Heavy condensation on the glass that doesn’t clear. In this case, remove any cork if there is one and leave the terrarium open until it settles. You could also place it outside for a day if possible as long as it isn't too cols. The process of moisture removal could take a few days or more, and is why it's very important to get moisture right in the first place.
You're more than welcome to reach out to us for a second opinion before you add more water to your terrarium, just in case!
Do:
- Consider picking up some aquascaping tools to help with trimming inside the narrow opening
- Keep the glass clean and clear (dust will block light)
- Remove any mould or dead leaves as soon as you spot them
Don't:
- Add water unless you’re sure it’s needed
- Move it around too much. Plants need time to adjust to the light
- Worry if things don't go perfectly. Terrariums, and especially Demijohn terrariums are learning projects!
Demijohns aren’t the easiest to access, so trimming can be a bit more of a chore than with other terrariums. If anything is pressing against the glass or looks like it's rotting, you should trim this back carefully with some long aquascaping tools. Most pruning is best saved for spring or summer, when plants bounce back faster, and remember most of the plants we use in our terrariums are easy to propogate so don't waste any cuttings!
Need Advice?
If you're not sure how your terrarium is doing or just want a second opinion, get in touch! Bring it into the shop, send us a message, or drop us an email. We're always happy to help!
In store we also offer various terrarium fixing services, such as trimming, plant replacement and complete rebuilds.