The vast majority of vegetables we cultivate in the UK are annuals, or are grown as annuals, meaning that a seed is sown, the plant grows, flowers, fruits, sets seed and dies in one year. The problem for the gardener is that the whole process of sowing seeds, tending to seedlings and warding off slugs and other pests from young tender plants must be repeated the following year in order to get a new crop. But if you want to adopt some permaculture principles in your garden, and grow some plants that will require minimal work and reward you with a crop year after year, perennial vegetables are your answer. The term ‘perennial’ simply describes a plant that completes its life cycle in three years or more. It covers the vast majority of plants, from the short-lived Lupinus perennis, which lives up to five years, to Taxus baccata, the Yew tree, known to live up to nine thousand years. Some common perennial vegetables include Asparagus, Artichoke, and Chicory and many plants that are grown as annuals are in fact perennial in their natural habitat (tomatoes, for instance) but here’s a selection of some of my favourite lesser-known species:
Allium sativum ophioscorodon (Serpent garlic)
Serpent garlic, so called because of its tendency to grow in serpent-like spirals, produces underground bulbs much the same as ordinary garlic, but the small bulbs it produces on its stalks in the place of flowers are also edible, have the same flavour, and the added bonus of being accessible without digging up the plant.
Levisticum officinale (lovage)
This is one of my favourite plants, and although it’s more of a herb – you’d add some stem and a few leaves of this to soup for a celery-like flavour rather than make a whole meal of it – the young leaves make a good salad.
Lovage dies down in the winter and the new leaves emerge in the spring, growing vigorously and reaching heights in excess of a meter within a few months. The plant divides well, so if anyone you know grows any, you can easily pinch some – just make sure you cut down the foliage before re-planting to encourage new growth. As well as being entirely edible (all parts can be used to make a digestive tea, the seeds can be ground and used as a spice or added to flour to give flavour in baking and the root can be cooked as a vegetable), it makes a beautiful addition to the garden and is a great companion plant, the yellow flowers being particularly attractive to bees.
Lactuca perennis (perennial lettuce)
Similar in appearance to dandelion (Taraxacum officinale) and chicory (Cichorium intybus), perennial lettuce produces mild-tasting leaves throughout the spring which turn slightly bitter as summer progresses. It flowers mid-summer, producing beautiful blue flowers, and can be treated as a “cut and come again” crop to ensure a continuous supply of the nicer tasting young leaves.
Brassica oloracea botyris aparagoides (nine-star perennial broccoli)
This is only just a perennial, normally living about 3 years, but an improvement on the ordinary annual broccoli most commonly cultivated. It produces a single white cauliflower-like head in the spring, and then several smaller heads from sideshoots. Like most members of the Brassica genus, it is susceptible to attack from the cabbage white butterfly.
Oxalis tuberosa (oca)
This root crop originates from the Andes can be grown and used in a similar way to a potato, but benefits from being particularly resistant to pests and diseases, and the tubers are capable of withstanding the cold to about -5°C. The tubers are formed in the autumn, needing a period of shorter day length to develop, so wait until the top foliage has been killed by frost before harvesting, instead of simply waiting until it has wilted as you would with potatoes. Your crop will also benefit from “earthing up”, or building up a layer of earth at the base of the foliage, to protect the tubers from the cold.
I want to mention this common species because despite being widely grown as an annual, most people don’t realise that it can easily be grown as a perennial in the UK. In the autumn, simply dig up the plant at the root and store it in a cool but frost-free place and re-plant in the spring. In mild winters (above -5°C) you could even leave the plant in the soil, covered with a thick layer of mulch and straw. Either way, you’ll get a much quicker crop the following summer than if you were to plant a new bean each year.