Turnips are grown mainly for their roots, which can be flat, round or long in shape, with white or yellow flesh. The leafy tops can also be used, and make excellent spring greens. By selecting appropriate cultivars, turnips can be available for use all year round.

Site and soil

Choose an open, unshaded site with fertile, well-drained and moisture retentive soil, which should be slightly acid (min pH 5.4, but see note on clubroot - add lime if necessary to adjust pH). Brassicas have a high nitrogen requirement and also need very firm soil. To ensure sufficient nutrient levels, it is best to topdress or apply a liquid feed such as seaweed fertiiser during growth.

Because brassicas are prone to soil infections, for example, Clubroot, it's important to use a minimum 3 year rotation plan.

Turnips like cool, moist conditions; summer sowings can be made in light shade, provided there is plenty of moisture in the soil. The soil should have plenty of organic matter worked in for the previous crop, or a top dressing of general fertiliser applied before sowing.

Cultivation

Sow thinly and successionally from mid March to mid August on well prepared soil about 2cm (¾") deep, early cultivars in 22cm (9") rows, winter cultivars in 30cm (12") rows. Thin gradually to 10cm (4") apart for earlies, 15cm (6") for maincrop. It is important this is carried out as soon as possible when seedlings are about 2.5cm (1") tall.

Keep soil well weeded and water in dry weather at 2 gals/sq yard per week.

Harvest

Early turnips mature in 6-10 weeks, and are best used small, as they deteriorate rapidly. They can be pulled like radishes when 4-5cm (1½-2") in diameter and eaten raw, or up to tennis ball size for cooking. Hardy cultivars may take 3 months to mature and are grown for autumn use and storage. They can be left in the soil until late December, then lifted and stored in soil covered clamps.

Turnips for spring greens

Sow thinly in rows 15cm (6") apart in August and September or as early in spring as soil conditions allow. The first cutting can be made when seedlings are 12-15cm (5-6") tall, about 2.5cm (1") above soil level. If left longer they become tough. Provided the ground is not allowed to dry out, several further cuttings can be made before they run to seed.

Pests and diseases

Most common is flea beetle, which can be prevented with crop covers.
Turnip gall weevil may cause hollow swellings on the roots, but is not generally serious. Discard galled seedlings.
Mealy cabbage aphid and cabbage root fly are other possible pests.
Mildew is the most common disease - increase aeration if possible and avoid overcrowding.