Kale and hearty

Apart from giving some really delicious and high-value crops, these are often beautiful ornamental plants and need less intensive maintenance than annual crops.

In the kitchen garden at Harlow Carr, we have Jerusalem artichokes, globe artichokes and cardoons, asparagus, seakale, good King Henry, and Chinese artichokes. There is also a large area for growing rhubarb, which is classed a vegetable rather than a fruit as the stem is the edible part. You probably do not have room for all of these, so go for one or two favourites.

Seakale (Crambe maritima) has the most beautiful glaucous, blue-grey leaves and stems.

The white-scented flowers in the summer are much-loved by bees. A member of the brassica or cabbage family, it is the delicately-flavoured blanched stems of the plant, forced under special pots (a bit like rhubarb-forcing pots), that are eaten. Like asparagus, it is good lightly steamed.

Forcing is done between autumn and midwinter and it takes two to three months to harvest, when stems are ten to 20cm tall. Seakale plants are grown from root cuttings or “thongs” planted in early spring.

Being seaside plants, they prefer sandy soil, so you may need to add grit or sand. These very hardy plants will need mulch in spring with well-rotted manure or topdress with low nitrogen fertilizer.

Helianthus tuberosus, or Jerusalem artichokes, are great winter veg, grown for their roots. They are related to sunflowers, but don’t always flower in this country. Originally from South America, not Jerusalem as the name suggests (a corruption of “girasole”, the Italian for sunflower), the plant forms tubers.

The tubers are a bit like potatoes, have a smoky flavour and are wonderful baked. They are sadly underrated, partly due to a reputation for being difficult to prepare – tubers can be fiddly to peel, although there are smoothershaped varieties, such as Gerard. They are also renowned for causing wind as a result of the body’s inability to break down some sugars, which is overcome the more you eat.

They are very easy to grow, but good cultivation with lots of organic matter and deep soil will result in better tubers. Equidistant planting at about 40cm gives good results. Plants can grow to 3m tall, so beware of shading other crops. We cut stems back by a third in winter to stop wind-rock damage. The plants are very hardy and tubers are best left in the ground until needed, and indeed flavour improves with the colder weather. To keep good stock going, select the best tubers and replant after harvesting.

ANOTHER striking perennial is the globe artichoke. Its spikey silver leaves and purple thistle flowers are gorgeous. It grows to about a metre and yields relatively little for the space, but it’s worth having if it is a vegetable you love. In this case, it is the flower buds that are eaten.

In France, the large flower base of the main flower head is the delicacy, with the fleshy bases of the bud leaves also eaten. The Italians tend to go for the smaller side buds as these are more tender, so there is less lost in peeling.

Once you have peeled the tougher outer leaves and scraped the stem, cut them in half and boil in lemon water until tender (the lemon stops them discolouring). Dipped in acidulated butter (melted butter with lime juice), they are an incredible seasonal treat. We have been growing a variety called Concerto, which is doing well.

Delicately-flavoured leaves

Again, this plant is not difficult to grow if you add organic matter to the soil to retain moisture, as well as mulch to control weeds and prevent the soil drying out. It is a Mediterranean plant, so protection from cold winds is a must, as well as good drainage. Propagation is by offshoots, so you can keep renewing your stock.

Generally it is best to keep perennials separate from the annual vegetables as the maintenance regime is different, and the soil preparation needs to be very good, as plants will be in situ for several years – up to 15 to 20 for asparagus.

Incorporate plenty of organic matter to enrich the soil and ensure good drainage.

Mulching with compost or manure to prevent weeds and to retain moisture is good practice, as is the removal of dead leaves and stems. Like herbaceous perennials, plants die back to ground level and resprout in spring.

Look after your perennial vegetables and, as well as looking gorgeous, they will reward you with wonderful crops for years. Seed catalogues and websites will be offering plug plants, root cuttings and tubers ready for planting up for spring, but beware, it is very easy to get carried away.