Kale, as it is commonly known, but you may find it under Borecole in seed catalogues, is originally from Northern Europe and is a member of the cabbage family. It has a very long history of cultivation with both the curly leaved and flat leaved forms of cabbages being known in the 4th century BC in Greece. Kale is probably the brassica that is closest to the original wild forms, and is tougher and resists pests and diseases better than the more highly cultivated forms of the brassicas.
While widely grown in much of Europe in the Middle ages, it may not have become common in the UK, until the 18th century. In Scotland, the kitchen gardens of Agricultural workers were known as “kail yairds”, where any “greens” grown were known as “kail”. In any event, Kale is very nutritious and is often used as a Winter feed for sheep on farms.
Kale is the ultimate hardy Winter standby greens, and will withstand severe frosts. It may droop at first with such cold but will recover when the temperature rises again. It is even said that frosts improve it’s flavour.
Kale is packed with healthy vitamins and minerals, such as A, K, C, B6, magnesium, lutein, antioxidants and only 27 cals per 80 g.
The seed is best sown in individual deep cells in March or April in a cool greenhouse. Transfer the seedling in the cells to a cold frame to harden off the young plants. During this period, ensure that the plants are protected with some small-mesh plastic netting, from cabbage white butterflies laying their eggs on the leaves. Also protect from slugs and snails.
The plants should be transplanted into their final positions in May or June, about 45 cm apart. During this period, keep the seed boxes well fed with a nitrogenous liquid feed. Remember to net against the birds. In the Winter, pigeons can strip every leaf overnight! When arranging netting protection, remember that the taller kales can grow up to 1 m in height. Protect from slugs, snails and Butterflies and their caterpillars. If you suffer from cabbage root fly, when planting out position carpet underlay disks around the stem.
Pests and diseases. It is said that kale is not so prone to the pests and diseases that attack other members of the cabbage family, but I prefer to take no chances!
Harvesting. It is the leaves that are usually eaten. Pick the younger leaves whenever you need some greens during the Winter, and lightly steam them or eat them raw.
In the Spring, you can harvest the unopened flower buds( see LHS photo) as well, and steam them just as you would steam sprouting broccoli. You can continue harvesting these flower bud shoots during April and May, when there is little else to harvest at this time.
Storage. Kale is best used fresh, but it will store for several days in the fridge crispator.
Kapitan F1. Mild taste, frilly green leaves but hardy.
Darkibor F1. Mild taste, frilly green leaves but hardy.
Dwarf Green. A curly variety with light green leaves that would be suitable for a windy site. A mild taste with a light peppery hint.
Redbore F1. A pretty, tall red curly leaved variety with a mild taste and slight bitterness.
Ragged Jack. A tall traditional, very hardy variety with mid-green serrated leaves with a hint of purple veins and leaf edges. It has a robust flavour with medium peppery after- taste.
Nero di Toscano. A classic Italian, dark leaved variety with upward facing leaves. Hardy with bitter leaves.
Black Magic F1. A modern hybrid, shorter with a mild flavour.
In the North of the UK, avoid Jagallo Nero, as it is not hardy.
There is a new British bred hybrid Kale/Brussels cross available which forms loose frilly-edged purple and green rosettes all up the main stem.
Petit Posy. Has a sweet mild taste of Brussels. Winter hardy. Continue harvesting the flower buds till June.