I’ve very recently purchased a polytunnel for my garden that I plan to use for growing vegetables and maybe a little fruit. I already have some outdoor vegetable beds, so I’m not short of growing space. But I’d really appreciate some advice on what kinds of crops you’d recommend for growing under cover. – Mary Heffernan, Co Dublin
Congratulations on your new polytunnel. These kinds of covered growing spaces give Irish gardeners what often feels like a magical advantage when it comes to greatly extending the growing season as well as growing tender or heat-loving species that can otherwise struggle in our cool, damp climate.
My first piece of advice is to grow only what you love. There’s little point, for example, in growing a bumper harvest of courgettes if you and your family don’t much like eating them. Also try to prioritise the space-efficient crops that are productive over a relatively long time (examples include tomatoes, cucumbers, climbing French beans, and leafy salad crops) over those that occupy a lot of growing space but only offer a relatively brief harvest window (examples include sweetcorn, squash and melons).
Ease of purchase versus difficulty of cultivation is another consideration. Aubergines and peppers, for example, are relatively difficult to grow well in Ireland, even in a polytunnel, so I’d suggest giving them a miss unless you can’t resist the challenge. On the other hand, a wide variety of salad crops can be grown quickly and exceptionally well in that same protected microclimate, soon saving you a small fortune, particularly if you successionally sow small amounts over the following months. These kinds of cut-and-come-again leafy crops will also be juicier and more tender, as well as less vulnerable to damage from slugs and snails than their counterparts grown outdoors.
Other popular kitchen crops, such as carrots, onions, Swiss chard, potatoes, beetroot, mange tout, sugar snap and kohlrabi will do just fine outdoors in the average Irish summer but are potentially worth planting under cover next spring to give you an early crop. The trick here lies in making sure that you don’t then find yourself with no free growing space available in late spring to plant your summer crops. As for fruit, possibilities to consider include a small fig tree and strawberries (both in containers) as well – if your polytunnel is large enough – a grape vine, or even a peach tree.
Discovering what works best for you is a delicate dance that gets easier with experience. In the meantime, I’d highly recommend getting your hands on a copy of The Polytunnel: Fruit & Vegetables All Year Round by Joyce Russell, written specifically with the Irish climate in mind. The Dublin-based organic gardener Nicky Kyle’s monthly blog (nickykylegardening.com) is another treasure trove of expert, timely advice for polytunnel kitchen gardeners.
