Kale

Overview

Kale or borecole – Brassica oleracea acephala

Rotation group – Brassicas

All the members of the kale family are winter hardy and grow on almost any type of soil with no problems. They are surprisingly tasty and a reliable source of fresh, healthy leaves all through the winter. There are two main types the curly leaf and the plain leaf cultivars. The borecoles are members of the curly leaved group.

How to grow

Sow

Kale is grown from seed. The seed can be sown in small pots or trays filled with fresh seed compost from May. When the seedlings are large enough to handle they can be pricked out singly in to 9cms/3in pots filled with fresh potting compost and grown on until they have produced four true leaves. At this stage they are ready to be transplanted 90cms/1yd apart in the row with 90cms/3ft between the rows. If space is tight the young kale plants can be planted 60cms/2ft apart; but the plants appreciate having the extra space and light between them to grow well. Plant them a little more deeply than they are in the pots so that the soil is right up to the bottom of the first set of leaves. Water the plants in and keep them well watered until they start to produce new leaves.

The seed can also be sown outdoors on a prepared seedbed from May to June. Take out seed drills 25mm/1ins deep that are long enough to provide you with sufficient plants to meet your requirements. Water the drill before you sow the seed thinly along the row. When the seedlings begin to produce their first rough leaves thin them out to 15cms/6ins apart to make sturdy plants. When they have produced 4 - 6 leaves (June – August) they are ready for transplanting as described above. Water along the row of seedlings the night before you intend to transplant them

Grow on

Kale like firm soil so they have to be heeled in after planting and push a strong cane or stake alongside the plants to support them later on against wind rock. The stake can also be used to support netting to protect the plants against pigeon damage. Water regularly and feed once a week with liquid seaweed to produce kale plants that will be strong enough to survive the Winter.

Aftercare

There will be plenty of bare earth in between the young kale/borecole plants at the early stages of their growth and although it is tempting to want to use is area it is more efficient to keep it clean and weed free to prevent a possible build up or pest and diseases. (see our weeds as hosts page). Keep tying the growing plants to the supporting stake/bamboo with soft twine. Draw the soil up around the base of the plants to support them and encourage stem rooting.

How to Harvest

Harvesting

The leaves will be ready to harvest from November until April. Cut them when they are young and tender.

Issues

Pests and diseases

Cabbage root fly is the main danger - it attacks soon after transplanting; the female lays her eggs close to the plants and as the young white maggots develop they eat their way along the roots causing the plants to collapse by day and seeming to recover in the cool of the evening. It is best to dig up any plants that show these symptoms and destroy them. A 6ins/15cm mat made from damp coursing may help as it forces the eggs to be laid too far away from the root system for the maggots to survive.

Large and small cabbage white butterflies lay their eggs on the undersides of the leaves and the caterpillars can quickly reduce the leaves to stalks. Small mesh netting suspended over the plants will give some protection but it does make working in between the plants difficult. Spraying the leaves with the biological pest control Bacillus thuringiensis will kill the young caterpillars without harming anything else. It is available from biological pest control suppliers.

Club root is the curse of any member of the brassica family and is impossible to control as it flourishes in poorly drained acidic soil. It helps to raise your own pot grown plants using John Innes soil based compost - not a peat based type.