Terraria are miniature versions of the famous ‘Wardian case’ which was an early type of mini greenhouse invented by a botanist called Dr Nathaniel Bagshaw Ward in the early 1800s. His original aim was to try and grow plants in his garden that were struggling due to the heavy pollution. The idea came to him after finding a healthy fern growing inside a discarded glass jar. His invention was so successful that similar glass cases began to be used by explorers and plant hunters to transport their bounty home from their travels.
There are different types of terraria that suit different types of plants but the beauty of all of them is that they can be small enough to fit easily into any home and can be a way of collecting and growing plants where an outdoor space is not available. They form their own microclimate and allow us to grow delicate species.
Some terraria are completely closed and practically airtight and work on the principle of the water cycle; water evaporating from plants collects on the glass sides and runs down to remoisten the compost or growing media. They are miniature ecosystems and fascinating to observe. This system is very suitable for ferns and other moisture loving plants that require a constant high humidity.
Open terraria are often constructed of leaded glass, larger ones with a wooden frame that will have some open sides and a decorative ‘roof’. Many of the traditional ones will reflect the Victorian ‘Wardian case’ style but modern ones can be funky or very geometric and may use stained glass.
You can purchase decorative bottles and jars of all shapes and sizes but you don’t have to stick to purpose-made vessels. Any glass vase, jar or bottle could be up-cycled into a bottle garden or terrarium as long as there is room to put your plants and other materials through the opening. Bottle gardens used to be very popular in the 1980s and if you keep your eye out in charity shops you can often pick up a bargain.
Whatever you decide to use or buy, planting them up is simple. You should use a good quality potting compost for both the open and closed types but for bottle gardens and closed cases it is important to ensure good drainage by adding a handful of sharp sand or horticultural grit or purchasing a compost with added loam. The addition of a small handful of charcoal will help to prevent the compost from going stale. Ensure that the compost is adequately damp but not overly wet. Plant up your mini landscape using ferns, small houseplants and suitable flowering pot plants. Add decorative features such as attractive pebbles or rocks, driftwood etc. Water in carefully.
Whichever system you choose, there is not a lot of room for compost so a little liquid fertiliser every few weeks will help your plants to thrive. Even the closed types will need a little top up of water every so often so take that opportunity to give them a little feed too.
Lee Bestall, Inspired Garden Design