Treasure in a bottle: your complete terrarium guide

Follow this method for any of the four terrariums we have created (below), but your start point in choosing plants will depend on whether you are making an open or closed terrarium.

An open terrarium has a similar environment to the rest of the room and will support the growth of most house plant types. Popular choices include succulents or kalanchoe. A closed terrarium will create it’s own microclimate suitable for plants such as ferns and mosses.

You’ll need:

• Closed terrarium: Jam jars with lids, Kilner jars.
• Open terrarium: any open glass jar or bowl
• Gravel (garden gravel or pumice and pebble dash)
• Activated charcoal (optional) can be acquired from aquarium supply stores and may reduce problems from bacteria
• House plant compost
• Plants: see individual lists
• Pebbles/decorative items
• Moss
• Scissors
• Cork stopper (optional) for tamping down compost around the base of the plants. Can be made by wedging a kebab stick into a wine cork
• Small paint brush for cleaning compost from the plants after planting
• Wide funnel (optional)
• Water: I just use a little misting bottle

Step one

Pour a 2cm layer of gravel to the bottom of your glass container. Any excess water will seep down through the gravel to collect at the base of the jar and then evaporate to moisten your compost once your terrarium is dry again.

Step two

Add a teaspoon of activated charcoal (optional). Scatter it over your gravel layer. For your terrarium layers to function properly they should be kept separate, so try not to mix up the different components, just gently layer them over each other.

Step three

Add a layer of potting compost. The layer should be deep enough to cover the rootballs of your plants. Fluff out the compost as you add it in. I use a long-handled spoon for this. Dampen compost.

Step four

Place your plants, use the cork to tamp down compost. Don’t plant too proud of the compost layer. If roots are exposed they will dry out. Add any decorative items, and moss if using, and close the lid.

Four terrarium ideas

Wild orchid

This is a closed terrarium. You don’t often see flowering plants in these type of terrariums but orchids do quite well. Use the miniature version. Remember orchids don’t flower all year around so don’t give up on it during its non-flowering phase. If the leaves look healthy then your plant is okay. Flowers will need to be removed as they die off.

You'll need: miniature orchid, Fittonia, Kilner jar, gravel and compost

Geometric

This contemporary style terrarium will suit a modern home. Take care not to damage the glass panes when planting. I’ve kept the planting simple and used a rock from my own garden as a focal point and to provide a contrast to the greenery.

You'll need: Geometric terrarium, rocks or pebbles from the garden, Pilea, Peperomia, sustainable carpet moss, gravel and compost

Apothecary style

These recycled, straight-sided vases are great for mini-landscapes, and allow easy access for pruning and watering, making them a good option for beginners. I’ve used a taller plant here to ensure that we don’t have lots of empty space above – and have added some minature sheep for a bit of fun.

You'll need: Large vase, Ficus microcarpa ‘Ginseng’ (bonsai fig), sustainable cushion moss (can be taken from a roof, or bought online or at a garden centre), gravel and compost

Fish bowl vase

Fish bowls are really easy to plant, which is great if you’re new to terrariums. This is also a great shape if you want to use larger decorative items, such as this castle I’ve chosen.

You'll need: large fish bowl, nodel castle – local aquarium store, asparagus fern, sustainable carpet moss, Fittonia, Pilea glauca, Peperomia, gravel and compost

FAQs: caring for your terrarium

How often should you water?

The commonest cause of death in a terrarium is overwatering! Your terrarium has no drainage holes meaning that excess water can’t run out of the container.

• Closed terrariums: Due to the naturally occurring recycling of moisture, closed terrariums are self-sufficient miniature ecosystems. You may occasionally want to remove the lid for cleaning, as the glass of closed terrariums naturally becomes cloudy over time and may reduce the view of your plants. If you remove the lid, replace lost moisture with a tablespoon of water and observe how your terrarium does. You’ll eventually get to know your plants and their preferred watering schedule.
• Open terrariums: Here, you will need to water the plants when the compost around the base of the plant feels dry. Dip your finger into the compost and if it comes up black and stuck to your finger then there’s no need to water. If the compost is dry, brown and flakey then it’s time to water. Typically, for a succulent terrarium, you would water once per week, certainly no more than twice.

Do terrarium plants need pruning?

Pruning is necessary to maintain the health and good shape of your plants. Remove dead leaves with sharp tools, such as scissors, in order to avoid damaging the plant. If leaves drop into your terrarium during pruning, remove them carefully with your fingers or tweezers. Don’t leave decaying matter in a terrarium. If plants are looking crowded, re-pot (I often do this after a year) and replace with new plants.

What's the best position for a terrarium?

Your open terrarium will like the light but do not place it near radiators or other heat sources. Don’t keep an open terrarium in a bathroom as there can be a lot of accidental water uptake here and your plants may suffer from inadvertent overwatering. A closed terrarium creates its own high humidity environment supporting plants that prefer woodland environments so can be placed anywhere.

What else should you add to a terrarium?

You can get creative by adding tiny figurines, signposts or even miniature buildings. We used a castle and miniature sheep, but you could keep it natural and use things from the garden or seaside such as pebbles, rocks and shells.