Kale (also known as borecole) has an undeserved reputation for being tough and bitter, but this because many people don’t know how to harvest it. Cut properly it will provide you with young, tender greens through the winter and well into spring, and even the young flower stems are tender and delicious – one of the best-kept secrets in gardening!
Now that the weather is warming up kale will eventually bolt, but don’t write the plants off just yet. The tender flower shoots are delicious steamed and tossed in herb butter – so pick them before the flowers open, and stretch your harvest out for another couple of weeks.
Kale is the least fussy of the brassica family and will grow in almost all conditions, even in sandy soils or part shade. For the best harvest it likes soil that was dressed well with manure or compost the previous season, and lots of sun. Sow the seeds about 1cm (1/2″) deep in rows 22cm (9″) apart and keep them well watered. When they have four true leaves (usually six or seven weeks after sowing) transplant them to their final positions at 45cm (18″) each way, planting them a little more deeply than the original soil level, and firm in well.
Kale is one of the strongest and least trouble-prone of all vegetables, but young seedlings are vulnerable to slugs and snails. If you are only growing a small number of plants, start them off in pots or modules rather than a seed bed but be careful to plant them out promptly. Like all brassicas the lower leaves turn yellow and die as the plant grows, and these should be removed as soon as this happens to reduce the hiding places available for pests. Kale may be attacked by whitefly in the autumn but this seldom causes these vigorous plants any problems: just give the leaves a good shake before you take them into the house. Some varieties may also be affected by mealy cabbage aphids, particularly in spring. These are best sprayed off the plants provided you spot them early, but can also be treated with insecticidal soap if things get out of hand.
Kale is a mainstay of cold-climate vegetable plots. Rich in antioxidants, calcium and vitamins C and K, it’s frost-hardy enough to overwinter without protection in most of the UK. In the far north it needs some protection, and in exposed northerly plots it should be shielded from the wind by mulching the whole plant with three to six inches of straw held down by a row cover during the coldest weather.
You can begin to take leaves from your kale plants as soon as there have been a couple of sharp frosts to bring out the flavour. Take only smallish, tender leaves from near the crown so that the whole thing ends up growing on a woody “leg”. Overharvesting stunts growth, so a few older leaves should be left to let the plant photosynthesize. Keep up with harvesting your kale because picking stimulates tender new side growth, increasing yields by around a third and delaying bolting. If you have too much it freezes well, and it also makes great fodder for chickens or rabbits.