Kale is a hardy and nutritious plant that can be a valuable food source over the winter months. Kale can be grown outside throughout the winter in much of the UK. If, however, you would like to be able to harvest kale in winter weather without frost and snow, or have a problem with birds eating your crop then a polytunnel can be a great option. A polytunnel will protect kale from the worst winter weather excesses and ensure you have a good stock of this healthy vegetable right through until spring.
Sow kale thinly between March and June where it is to grow or, from March, sow seeds indoors and transplant kale seedlings to their final growing position when their first few true leaves have formed. Sowing indoors can be a good option where delicate young seedlings are lost to pests. Cloches can help protect seedlings while they are still small. Once it begins to mature, kale is a hardy crop that is able to take care of itself.
Seedlings should be placed, or thinned to around 7.5cm apart initially and then thinned to or placed at a final spacing of around 45cm between plants. Puddle in plants with plenty of water and continue to provide plenty of water over the growing season. A nitrogen rich organic mulch will help to conserve soil moisture around your plants and will also encourage good, leafy growth. Grass clippings and good quality compost make a good mulch for kale and other brassicas.
As a brassica, kale will benefit from nitrogen fixing plants sown nearby. Kale will also grow well as a companion crop for beetroots and spinach, amongst other crops. Onions, nasturtiums and thyme may all benefit kale by reducing the incidence of some pests.
Kale can be harvested as a cut and come again crop for salads and stir fries, or left to mature and used in the same way as other cabbages. Usually, it is best to remove young leaves from the top of the plant from October onwards and then to continue to harvest as needed over the winter. As a cut and come again crop, you can begin to harvest when plants are around 5cm high, when further young leaves will be formed which can also be harvested in turn. There are plenty of ways to use kale in the kitchen. One child-friendly kale recipe is kale crisps, made in the oven. This is a great way to get some nutrition into those who are not so keen to eat their greens.