Kale is a brassica which improves with the cold in flavour and colour

NOW that the winter weather has arrived and temperatures are falling, our thoughts turn naturally to comfort food: nourishing and warming oven bakes and stews.

Many crops in the vegetable plot are over, but one of the most hardy and useful winter crops is kale. This member of the Brassica family – closely related to cabbages and sprouts – can provide veg nearly all year round, from salads to winter leaves. Its attractive and strong structural form make it a highly decorative element in the kitchen garden, and with increasing cold, it just gets better – both flavour and colour-wise – providing fresh greens when they are really needed.

From fashionable, strongly-flavoured Cavalo Nero – or Tuscan kale – with its long, dark green leaves, to frilly green-leaved varieties like Reflex, gorgeous purple Redbor and smoother-leaved red-tinged Red Russian, a good choice for salad leaves, there is a kale for everyone. For smaller plots, Dwarf Green Curled could fit the bill, or simply grow smaller kale plants for young leaves or salad.

And the good news for those of us growing in this area is that kale prefers the cooler seasons and grows well in most soils, even our heavy clay at Harlow Carr, though it does appreciate the addition of some organic matter. The main weather protection needed is from wind-rock – kales are big, top-heavy plants, so we stake them in winter with a tripod of hazel or birch branches.

Kale is traditionally sown in May to June to give plants the chance to harvest over the autumn and winter period and develop full-sized plants. By planting out in July, kale can follow early potatoes, spinach, carrots or salad leaves in the kitchen garden. Sowing in July will give smaller plants for use as young leaves. Sow in a seed tray, but beware: it’s easy to end up with too many plants, and prick out into small pots, planting deeply to ensure a well-firmed seedling growing on.

After hardening off well, plant out firmly up to the seed leaves; kales will become large plants so need a good anchorage. Branches of twiggy birch or hazel can be used to form a tripod around young plants, protecting them from wind damage and pigeons. Spacing can be quite close; try 35cm for young salad leaves, and up to 60cm for full-sized curly kales. Slugs can be a problem for young plants, so ensure your specimens are well hardened off; we use nematodes in our raised beds to reduce slug populations. Netting can be used to protect from cabbage white butterflies, using hoops and green or black netting, so it’s less conspicuous. Collecting fallen yellowing leaves keeps plants clean and can also reduce whitefly attacks.

Groups of kales can look stunning when planted together, mixing their colours and textures as well as tastes, but you don't need to grow more than three or four plants unless you are a real kale fanatic. Any spare seed can be used to grow baby salad leaves: sow in drills or scatter sow outside.

Many visitors ask what on earth to do with all that lovely kale and how best to cook it. Preparation is straightforward: harvest several younger leaves from your plants and rinse them carefully, getting rid of any whitefly by adding a squirt of lemon juice to the water. Strip the leaves from the tougher midrib, then steam lightly. Overcooking will produce the classic cabbage smell – sulphur compounds released by all brassicas -,and will result in a loss of texture and vitamins. If using in a stir fry, chop up the stalks as well and cook them for slightly longer. Add the steamed leaves in with roasted pumpkins, sweet or ordinary potatoes, and use with warming spices such as toasted cumin, sweet paprika and chilli. Nigel Slater also adds cheese – goat's cheese is particularly delicious. Stir fried with toasted sesame and black mustard seeds, butter, lime juice and zest, or in a curry with chickpeas, mushrooms, coconut milk and lime, this is a truly wonderful winter veg, its colour and flavour making you feel healthy and happy, even when the weather is miserable.

Jobs to do

Tidy up tender plants that have been hit by the frosts, including dahlias – lift the tubers clean off soil and store frost-free over winter

Make sure any vulnerable plants are protected by fleece, earthed up etc

Stay indoors and enjoy looking through seed catalogues for next year, planning what to grow!

For more information on things to do in the garden this month visit rhs.org.uk

DIARY DATES

Friday, December 11, 10am to noon: Guided Winter Walk

Discover winter garden inspiration on a guided walk and talk with Garden Manager Katherine Musgrove. Visitors can find out how to brighten up their own garden and learn about the plants, shrubs and berries used to provide seasonal winter colour in the woodland, Winter Walk and ornamental borders at Harlow Carr. The walk ends with a mince pie, a warm drink and a potted holly to take home. RHS members £25, non-members £33. Call 020-3176-5830 to book.

December 11 to 13 and 18 to 24: The Magic of Christmas

Decorate a gingerbread man, write and post a letter to the North Pole and explore the garden on a Christmas trail. Don’t forget to add a wish to the festive Wishing Tree. Families can also enjoy the creative handiwork of the Harlow Carr elves – otherwise known as the garden team – who have been spreading Christmas cheer by decorating trees, planters and garden structures with more than 500 stars made from willow. Normal garden admission.

Friday, December 11 and 18: Christmas Stories with Santa

Under-fives are invited to snuggle up for a classic Christmas tale or enjoy a sing-along with the man himself at Harlow Carr’s popular Stories with Santa sessions which take place in the beautiful setting of the historic Bath House. If youngsters have been very good this year, there’s even a small gift to take home. Places are limited and must be booked in advance by calling 0844 581 0783. Additional fees apply.