One of the best things about having a vegetable patch is the ability to grow crops all the year round. Once the summer harvest has been collected, you can fill the site with plants that will produce tasty vegetables such as fresh leeks, broccoli (calabrese), kale and Brussels sprouts over the winter months.

Sowing

Winter crops are hardy and may survive in temperatures as low as -12°C (10°F) and may be sown directly into the open ground. However, instead of sowing them directly into their final growing place where they may take up space that could be used by summer crops, make a separate seedbed to start them off then move them once the summer crops have been harvested.

The seed should be sown in spring (March-May) into moist seed drills 1-2.5 cm (1/2-1 in) deep and spaced 15 cm (6 in) apart. You should try to aim for a gap of 5-10 cm (2-4 in) between each seed. When you have covered the seed drill with soil, protect the emerging plants from bad weather and pests with a sheet of garden fleece; this may be removed as the weather becomes warmer.

As the seedlings develop, pull out any weak or spindly plants, leaving the strong plants at the correct spacing. This spacing will vary, so always check the seed packet for advice. Kale should be given a nitrogenous top-dressing to encourage growth.

Transplanting

In the summer (June-July) the young plants can be moved and planted in spaces left by harvested summer crops. Water the seedbed well, and then lift the plants out gently, disturbing the roots as little as possible.

• Brussels sprouts: Space 60 cm (24 in) apart.
• Calabrese (broccoli): Space 60 cm (24 in) apart and apply nitrogen-based fertilizer.
• Kale (dwarf): Space 30-45 cm (12-18 in) apart.
• Kale (tall): Space 75 cm (30 in) apart.
• Leeks: Plant in holes 15-20 cm (6-8 in) deep, 15 cm (6 in) apart. Fill the hole with water and allow the soil to fall in as the plant grows.

Winter-grown vegetables may be very vulnerable to pests such as pigeons and rabbits, so you may need to protect them with netting.

Harvesting

• Brussels sprouts: Can be harvested 20 weeks after sowing, although their nutty flavour is often enhanced if subjected to frost. Collects the sprouts from the base of the plant; the upper sprouts will continue to develop.
• Calabrese (broccoli): Ready to harvest in 11-14 weeks after sowing. Cut off the main broccoli head when it is 7-10 cm (3-4 in) in diameter and before the flowers begin to open; this will encourage the sideshoots to develop. These should be harvested when they reach 7 cm (3 in).
• Kale: Most cultivars can be harvested 7 weeks after sowing, but may be left to stand in the ground for some time. Snap off leaves during autumn and winter to encourage new growth.
• Leeks: May be harvested 16-20 weeks after sowing, but may be left to stand for many months. Leave in the ground until ready to use.