Introduction

Root vegetables, as the name suggests, are mainly grown for their swollen roots or tubers. Some, like beetroot and turnips, are also grown for their young leafy growth. Some radish cultivars also produce edible seed pods. Most root vegetables may be grown and harvested in succession for a regular supply. Most will also store well, some still in the ground. Most root vegetables are biennials grown as annuals. Root colour and size depend on the genus or species grown. Generally carrots are orange, red or gold in colour. Swedes and turnips tend to be cream, white and pale gold, swedes tending to have dark skins. Beetroot are generally dark red but also come in yellow and white, some with rings of colour.

Cultivation

Root vegetables often like a well dug soil that has been well fed in the past. Beetroot may require extra nitrogen fertiliser, applied prior to sowing as a base or soil dressing, then again during the growing season. Carrots and turnips require very little feed, as this can cause the roots to branch or split.

• Beetroot (Beta vulgaris)
• Carrots (Daucus carota)
• Swede (Brassica napus)
• Turnip (Brassica rapa)

Sow seed in situ in spring, in an open site. The soil should be workable and warmed to at least 7C (45F). Sow the seed 1-2cm (½-¾in) deep. The spacing will depend on the variety or type you are growing. Early crops may be started under cloches or in frames. Thin the seeds as necessary. Sow every two or three weeks for a continuation of cropping. Sow late summer if you wish to store the crop, but at least 10 weeks before the first heavy frost is expected.

Roots can be harvested at any stage; depending on variety, this may be from 7 to 13 weeks from sowing. The roots may be left in well-drained soil over the winter, protected by a 15cm (6in) layer of straw. They do however soon become woody. Carrots and turnips are best lifted before severe frosts and stored in moist sand in a frost-free place. They generally keep until mid-spring. When lifting beetroot, the tops should be twisted off as cutting causes 'bleeding'.

NOTE: Most beetroot seeds are clusters of seed containing two or three seeds. These require thinning out early to avoid root disturbance. Some varieties have been bred to only produce one seed and are called 'monogerm' seeds.

Keep the rows weed free and in dry seasons extra watering may be required (11 litres/sq.m - 2 gallons/sq.yd.) Carrots may require a little more.

Pests and Diseases

Carrot root fly is one of the biggest pests of carrots. Thinning should be done in the evening, by nipping off the green leaves and removing them from the site. Resistant varieties such as Carrot 'Fly Away' are also available. Birds, mice and green flies can also cause problems. Boron deficiency is sometimes seen in root vegetable crops. This causes leaf yellowing and scorching. It is very rare if general purpose fertiliser is used that includes trace elements such as boron, magnesium, manganese, iron and molybdenum.