Although the root is normally round, cylindrical root shapes are not uncommon in earlier varieties and colours can range from white to yellow and purple.
Where to grow turnips
Turnips thrive in firm, fertile soil that retains moisture. Dig in the autumn and incorporate plenty of well rotted manure or garden compost to help retain moisture.
Grow best in a sunny position but can tolerate some degree of shade.
As always, especially with root crops, rotate your planting to avoid soil-borne pests and diseases.
For an early crop, start by sowing under cloches in late winter - Easy Tunnel or Lantern Cloches would both work well and will also help protect spring sowings from particularly harsh spells of weather.
Sow thinly in rows 1cm deep with 20 cm between rows. For the early crops and thin to around 15cm apart after germination. Successional sowing during spring and summer will ensure a steady supply.
For turnips to be harvested in autumn or winter sow in late summer to the same depth but thin to 20cm between rows for a slightly larger root.
Water regularly to prevent bolting. Keep rows weed free using a Speedhoe
Harvesting and Storage
Pick turnips harvested in summer when they are the size of a golf ball - don't allow them to become woody and they will taste better when picked young.
Leave autumn and winter varieties in the ground and harvest when required. Alternatively lift and store in moist sand in a shed or garage or even easier, in a natural jute bag such as the Haxnicks Vegetable Sacks. (Great for your potatoes and carrots too!)
Turnip Pests and Diseases
They are prone to the same pests and diseases as cabbages; mainly flea beetle. You should avoid growing in ground previously used for brassicas and cabbages, considering turnips in the same group when planning crop rotation.
Violet rot and clubroot can be a problem which can be prevented by good crop rotation. To combat it destroy any affected plants on the bonfire or dispose of away from the garden.