How To Plant A Terrarium
Plant a low maintenance miniature garden for your windowsill
A terrarium is a self-contained garden in a glass container. The container can be sealed or open-topped. If it is sealed it will re-cycle the water which will mean that there is virtually no maintenance. The plants are watered well after planting and the lid put on the container; water evaporates, condenses on the inside of the glass and trickles back down into the compost. They first came into being in the mid-1800’s when a chap called Nathanial Ward first wanted to study the transformation of a chrysalis into an insect. He placed the chrysalis into a large, sealed glass bottle where a fern seedling grew. This fern continued to grow in the bottle for 4 years with no maintenance, during which he wrote a book on the subject with the result that ‘Wardian’ cases became immensely popular in the Victorian era.
Choosing a container
This will depend upon what you want to plant, or could be something you already possess. The size can vary from a brandy glass to a second-hand sweet jar. A container with a narrower neck than a base is preferable as any moisture will condense and run back into the compost. If the sides are straight it tends to just evaporate into the atmosphere.
Place a layer of gravel or expanded clay pellets in the bottom, about 2.5cm (1”); scattering some charcoal over this will keep the compost sweet and prevent it stagnating. Add a layer of compost, use a dedicated houseplant medium. Try and keep the layer of compost in proportion to the size of the container. Position the plants with the tallest at the back, if it is going against the wall, or in the centre if it is going to be viewed from all sides. Scale down the plants in height with any creepers at the edge. Top off the compost with a mulch of moss, sand or mini chipped bark, depending upon the planting style. Water well after planting, but not so much that the plants are stood in water.
Feeding and watering
Don’t feed in the first year as there should be enough nutrients in the compost and feeding would only result in the plants out-growing the container. In subsequent years feed with a houseplant food spike pushed into the compost. Change the compost every 3 – 4 years, and probably by this time the plants will have out-grown the terrarium. Mist the plants occasionally to maintain the moisture level. They will need very little watering, just make sure the layer of gravel stays wet.
Choosing a style
The traditional terrariums are usually just a mixture of foliage plants with a flowering plant to inject a shot of colour but you can have a terrarium of all flowering plants; a desert scheme with cacti and succulents, stones and sand or a mini herb garden. You can also make a carnivorous garden; just make sure the opening is large enough to ensure insects can enter. Ferneries are easy to make and require hardly any maintenance.
Small, slow growing plants are best as they will not outgrow their surroundings for a few years. Choose a variety of heights, leaf shape and colour. For colour use African violets and Kalanchoe or keep changing the plant with the seasons: Narcissus ‘Tete-a-tete’, Muscari and Cyclamen, to name just a few. Your local garden centre will always have something colourful. Just remember if using the Kalanchoe don’t keep the compost too wet otherwise it will rot.
- Begonia rex
- Chamaedorea elegans (Parlour Palm)
- Dypsis lutescens (Areca Palm)
- Helexine (Baby’s Tears)
- Maidenhair fern
A small herb garden would be ideal for the kitchen windowsill, just don’t site it in full sun otherwise it will dry out too quickly and end up being high maintenance.
Just use a selection of small ferns and moss to give that forest floor feel. These work particularly well in a sealed container and as a result are very low maintenance. They are also ideal if the terrarium is to be sited in a position which does not receive much light.
Choose a selection of small plants and moss as most of these plants grow in a damp mossy environment. These don’t mind soggy compost, just make sure the insects can easily enter the container otherwise the plants will starve.
Choose a mixture of small cacti and succulents and decorate with sand and stones. Unlike all the other types of terrarium, make sure the compost is very free draining by using a dedicated cacti compost or mixing John Innes Potting compost 50/50 with sharp horticultural sand. Don’t use builder’s sand as it contains harmful salts. Top dress your finished arrangement with sand to resemble the desert. This is one of the easiest arrangements to look after as it needs very little water and only a weak cacti feed every couple of months.
These don’t need any compost at all so you can use any type of stones, decorative gravel or glass pebbles. They need a humid atmosphere so a container with a narrow neck or closed completely would be ideal. Just keep the water level about half-way up the gravel so that it provides humidity but is low enough not to touch the plant. These will benefit from regular misting in summer.
Choose a plastic container which looks like glass, as it is safer for children to handle. Make sure the top is wide enough for the children’s hands. A budget option is to use a 2ltr plastic drinks bottle, making sure it is well washed out before use. Cut off the bottom 20 – 25cm (8 – 10”) of the bottle and plant up then cut the bottom 15cm (6”) off another bottle to use as a lid; cut slits around the rim of the lid to enable it to fit over the planted bottom section.
Try planting with carnivorous plants and moss and putting in a small plastic frog or lizard; the top will have to be left off this as insects need access.
Ferns are also an easy maintenance option; as they are pre-historic plants you can incorporate dinosaurs.
Succulents make an easy maintenance terrarium as they are very forgiving if not watered; avoid the spikey cactus, getting spines in your fingers could put a little one off gardening for life! The lid must be left off succulents otherwise the arrangement could become too humid and the plants rot.
New in to our Pets and Aquatics Department is the biOrb Air, a fully self contained terrarium which automatically mists when humidity levels start to drop. It also has a feature which prevents condensation forming. It makes a fantastic focal point for any room and is ideal for anyone who loves plants but is too busy to care for them.
If you love houseplants you may be interested in the blog articles: 'Best houseplant for a shady area', 'How to spot when your houseplant is diseased' and 'How to spot when your houseplant is infested with pests'.