Having a greenhouse can ease the guesswork when it comes to growing plants that may not survive outdoors, writes Elly West, who this month shares the benefits of having your own at home, as well as tips on what to sow this month.
Gardening in the UK, as we all know, is very much driven by the weather. Last year I ate blackberry and apple crumbles for weeks on end, boxes of fruits were a regular sight at the end of people’s drives in my village with ‘please help yourself’ signs, and the trees were laden, driven by a warm sunny spring that boosted pollination, followed by a hot summer.
We don’t know yet what this year will bring, given our unpredictable climate, but having a greenhouse can remove some of the guesswork and give us a little more control, extending the season and allowing us to grow more tender plants that may not survive our outdoors.
The smell of a greenhouse is evocative of summer, that leafy, warm, damp scent that often takes us back to childhood. For me it’s pelargonium leaves and tomatoes, grown by my grandfather. Stepping into his greenhouse felt a bit magical, a warm, sunny den in the garden where you were instantly surrounded by lush green leaves and trays of who-knew-what.
Greenhouses, along with orangeries and conservatories, are largely a northern-hemisphere phenomenon, and references to ‘forcing houses’ and covered gardens can be found dating back to classical Greek and Roman times. Roman emperor Tiberius was supposedly told he needed a cucumber a day for his health, his gardeners then cultivating them in beds mounted on wheels, which, in cooler months, they could move under frames glazed with sheets of selenite – a transparent rock that let the sun in.
As glass became more widely available from the early 17th century, greenhouses, or glasshouses, became the private playgrounds of the rich, used to grow fruits and flowers. Aristocratic Victorians are well-known for their love of plant collecting and tropical rarities, and structures similar to the Palm House at Kew were built at many stately homes, heated by hot water and allowing the cultivation of tropical plants and fruits such as the coveted pineapple.
By the early 20th century, small self-assembled glasshouses were widely available to everyone with the space and money to buy, and further advances mean today’s greenhouses are relatively inexpensive, giving anyone with a little bit of space the opportunity to grow plants undercover.
Whether you are wanting a full-on orangery-style glasshouse, or a small polythene growhouse or coldframe, one of the keys to success is where it is placed. A glass greenhouse is heavy and requires a solid base in a spot where it gets plenty of light, particularly in winter. An east-west orientation is generally preferred, while a lean-to is best on a south or west-facing wall. Another big decision is whether to have a heated greenhouse or a cold greenhouse. In mild areas, a cold greenhouse can be all you need to give plants and seeds the best start in spring, protecting them from mild frosts and wind, although overwintering tender plants is still going to be a risk. Heated greenhouses cost more to run and need an electricity source, but allow year-round cultivation of a wide-range of plants, including citrus fruits and orchids.
At this time of year, the greenhouse comes into its own, providing a space to start off seeds for early sowings of flowering plants and veg. Cool-season leafy greens such as lettuce, spinach, kale and rocket can be sown now, and with some heating you can also grow more tender crops like tomatoes, peppers, courgettes and beans, ready for planting outside later on. Other more hardy veg, such as spring onions and radishes, will benefit from a head start in the greenhouse in early spring, as will many herbs, including basil, coriander and parsley.
In terms of flowers, now is the time to start growing summer bedding in the greenhouse, such as snapdragons, petunias, cosmos, zinnias, marigolds and dahlias. Young plants bought in trays at the garden centre or supermarket can also be grown on and hardened off before they go outdoors once the risk of frosts has passed.
Another advantage of greenhouse growing is protection from pests. There’s nothing more depressing than discovering a slimy slug or snail trail across your carefully grown seedlings, and a greenhouse bench is a much safer spot than the bare soil. Watering is also more controlled, and plants dry out less quickly in a humid environment. Aim to water in the morning and consider simple automatic systems such as capillary matting under your seedling trays, or drip irrigation from a water butt. High humidity can lead to fungal diseases though, so good ventilation is also vital.
Greenhouses can be attractive features in their own right, blending function and beauty. A greenhouse can be a quiet retreat and somewhere to sit and relax with the addition of a small chair, cushions and perhaps some solar fairy lights for when the sun goes down. Wooden structures can be painted in soft heritage colours, and think too about the area around the greenhouse, perhaps framing the entrance with climbers or potted plants, or positioning it at the end of a path so it draws the eye and provides a focal point.
Elly West is a professional garden designer, working in and around the Bath and Bristol areas; find her at ellyswellies.co.uk
