Terrariums are worlds in miniature – tiny verdant landscapes that offer all the visual pleasure of a garden with minimum fuss.
They may seem purely ornamental, but terrariums changed the world. It was the accidental discovery in 1829 that plants thrive in a closed glass container that allowed previously unknown species to survive long sea journeys when new countries were being discovered. Rubber plants, bananas, tea, mangoes and orchids were among many that became widely grown because of this technology.
Closed terrariums are self-nourishing and regulate their internal climate. The soil and plants release water vapour that collects on the walls of the container and trickles down. Open terrariums are not very different from a pot plant and need much the same attention.
Making a terrarium is creative and fun and only limited by what will fit in the container. You can create landscapes or scenarios with minuscule figures – scenes from films or daily life – or perhaps just lush woodland worlds rich with the textures of moss and ferns.
How to make a terrarium
You’ll need a glass container, such as a large bottle, vase, fish tank or bowl and a way of sealing it. You may need long tweezers to place the plants and other items, depending on the size of the opening. Bear in mind that if the opening is too small, it will be difficult to place and manoeuvre plants and stones. If you are creating a complicated scenario, plot it out on the table first, so you know where everything is going and to avoid having to pull plants out and re-set them.
Fill the bottom of the container with a layer of charcoal or gravel and half the amount of the potting mix you plan to use. Add large stones, and any big ornamental features you are using, and make holes large enough for the plant roots. Position the plants and add the second layer of potting mix around them. The level should be about the same as the soil of the plant’s original root ball. Using a spray bottle, moisten the soil. Fill in the gaps with moss or small gravel.
Which plants work best?
You want small, slow-growing indoor plants and small succulents. Ferns, moss, sedums, mondo grass, small begonias and peperomias, or radiator plants, with their stripes and colours, are all good. Check that the plants you choose have similar light and temperature requirements. The Venus flytrap, that fascinating carnivore, is a lot of fun and difficult to grow other than in a terrarium.
Where do I put it?
Most terrarium plants like indirect sunlight. Be careful of putting your terrarium directly in the sun as it may be too hot. As a decorative element in your home, the only restriction is your imagination. Mount terrariums on the wall, hang them, use them in the bathroom or make a feature of several together.
How do I maintain my terrarium?
Terrariums can last for years. You may need to spray lightly with water about once a month. Check the soil before doing so and, while you are in there, remove any yellow or brown leaves. This is usually a sign of disease or pests and the plant may have to be replaced.
If there is condensation, stop watering. Can’t get your hand in to feel the soil? Pick the terrarium up and see if there is moisture in the bottom. If there is, don’t water. And if you accidentally over-water, just leave the top off for a few days.