Offering more than twice the amount of vitamin C as spinach; three times richer in carbohydrates than lettuce; containing 28 times more Vitamin K than carrot; packed with fibre, iron, calcium, and being low in calories and high in water, kale is the undisputed king of the winter vegetable garden! 

Packed with goodness, and remarkably hardy, superfood kale can be harvested throughout most of the winter, even after hard frosts and snowfall, when there is not much else growing in the vegetable garden. It does in fact, along with parsnips, carrots, and leek, taste better after being touched by a hard frost or two.

Kale is one of the easiest leafy brassicas to grow, thrives in any well-drained, fertile soil, and resists most of the common brassica problems.

If you want to be harvesting kale this time next year, get ready to start sowing seeds in the new year.

Sowing

Kale is generally sown between March and June, to be ready to harvest from September onwards. 

Sowing Indoors

Kale needs plenty of room to develop properly, and is slow to grow. To make the most of the space you have it is better to start plants off in plug trays or pots in order to establish the seedlings while other crops are still using the space in the ground. 

Fill module trays or small pots with multipurpose potting soil. Firm it in with your fingertips then make holes about 1cm (1/2in) deep. Sow two seeds per plug or pot, cover, and water. Should two strong seedlings germinate,  remove the weaker of the two.

Sowing Outdoors

If you choose to sow outside, choose a sunny position in order to encourage stronger growth during the dark winter months.

Prepare the sowing site by weeding thoroughly, and raking the soil level. Draw out a shallow drill, 1cm (½in) deep, then water along the base. Sow the seeds thinly along the drill. If sowing more than one row, space them 15cm (6in) apart.

Once seedlings germinate, thin them out to 7.5cm (3in) apart, to prevent overcrowding as they grow. The thinnings can be used as baby leaves in salads.

Transplanting Kale

If sown indoors, transplant young kale plants to their final growing position when they have five or six true leaves, spacing the young plants about 45cm (18in) apart as they need plenty of room to grow. 

Dig a hole, pop the plant in, and backfill with soil. Kale needs to be well anchored, so be sure to properly firm the plants into position so that so their lowest leaves are at ground level. Water generously, and apply a mulch around the plants to help hold moisture in the soil. 

It is a good idea to protect the plants from birds by covering with netting or fleece.

Kale grows well in containers as long it is planted in a well-draining potting mix.

Caring for Kale

Get the most out of your harvest by regularly feeding plants with a continuous-release plant food.

Keep plants well watered during dry spells, especially during the summer as they settle in and establish. Remove damaged or yellowing leaves as they appear.

Kale’s roots run horizontally from the central stem. Use straw or a grass mulch at the base of your plants to keep the soil cool, conserve moisture, and make it easier for roots to feed.

Harvesting Kale

It is time to harvest when the leaves are about the size of your hand by taking one or two leaves from each plant. Kale can be grown as a cut-and-come-again crop so start with the lowest, outermost leaves, and work toward the centre so that the central inner rosette of leaves remains untouched to encourage growth.

If left to mature for winter greens, plants can remain in the ground through the winter, picked as required for soups, stews, or kale crisps. Remember leaves reach their peak flavour once they have been kissed by a light frost.

By the end of the following spring kale plants will have grown quite tall as a result of this regular harvesting. When they stretch to flower they can be removed to the compost heap, or left as an extra source of nectar for pollinators.

Did you know?
While kale is generally considered an annual crop, there are some perennial types, that will regrow year on year.

Storing Kale

Kale leaves are best used when freshly picked. They can however, be blanched, and then frozen to store for later use.

Pests

Fuzzy, grey cabbage aphids are a common problem, often gathering in clusters within the folds of frilly kale leaves. Treat small problems with insecticidal soap, pick off and discard any badly infested leaves, and use an insect mesh covering as a simple way to protect plants.

Kale Varieties to Try

‘Cavolo Nero’

One of the most popular varieties due to its hardiness, strong flavour, and long cropping period. It produces dark green, long, plume-like leaves that look great in winter, particularly when dusted with frost.

‘Nero di Toscana’ or ‘Black Tuscany’

This kale is great for spring greens or left for winter cropping. It has green, crinkled, strap-like leaves.

‘Redbor’ AGM

If you are looking for a more colourful addition to the veg garden, this hardy kale has vibrant purple leaves, and tastes sweeter after frost.

‘Ragged Jack’ or ‘Russian Red’

This heirloom variety produces frilly, red-tinged leaves which really makes it stand out on the plot all year long.