They are also related to Swedes although they are two different species.
Most varieties of turnip are white-fleshed whereas Swedes are generally yellow fleshed.
The reverse can be equally true i.e. there are also white fleshed swedes and yellow fleshed turnips.
The leaves are somewhat rough, with sparse stiff hairs over them whereas, those of the Swede are smooth like cabbage leaves.
Turnips require a shorter growing season than Swedes, and this attribute makes it suitable for successional sowings.
Like swedes, turnips are sensitive to hot weather, which makes them well suited to growing in the UK.
They are a fast crop,they can be ready for harvesting in six to eight weeks from sowing.
Pick them when they are about 75-10mm (3"-4") in diameter when they are at there most succulent stage.
If allowed to grow much larger,they become less flavoursome.
Successional sowing every two or three weeks will ensure a constant supply of young and sweet turnips.
Turnips are of the brassica family and as such need similar soil conditions.
That is they will grow in most types of soil providing it is fertile, free draining and has a Ph of around 7.0 to 7.5.
Because turnips are faster growing than swedes, this pH level is not as critical as it is with swedes, somewhere around 7.0 would suffice.
The soil should be well prepared with the addition of well-rotted manure at least a month or so before sowing.
Add a top dressing of a general fertiliser at a rate of 80gms (3oz) per sq m at sowing time.
Pests and Diseases:
As members of the brassica family Turnips may suffer from the same pests and diseases, however, again due to their speed of growth, they are less susceptible than swedes.
The most common examples are ;
Aphids: where the symptoms are; curled leaves and twisted stems.
Club Root: Where the leaves droop and the roots become distorted.
Downy Mildew: Is seen as grey patches and wilting leaves.
Flea Beetle: Tell tale round holes in young seedlings.
Slugs and Snails: The leaves will often be quite tattered.
Week 15: Sow seeds in the open for an early crop, choosing a south facing plot.
Protect the plants with cloches if the weather turns cold.
On completion apply a top dressing of carbonate of lime at the rate of 150gms (6oz) per sq.m on all but limy or chalky soils.
Germination will take 5-7 days.
Week 21: Make successional sowings of summer varieties monthly from now until August.
As with most root crops a friable, light soil suits turnips best, but any fertile soil rich in phosphates is suitable.
Add a top dressing of Superphosphate and bone-meal at a rate of 100gms (4oz) per sq m prior to sowing.
Sow seeds in 12mm (½") deep drills drawn 400mm (16") apart.
Week 27: Thin the seedlings as soon as they are large enough to handle and then again as they grow.
Allow 150mm (6") between summer turnips and 250mm (10") between autumn and winter varieties.
Week 29: Give the young plants a thorough soaking once a week during prolonged dry weather.
Harvest summer turnips when young, pulling them as they are required.
Week 35: Make a late sowing of hardy maincrop turnip varieties for a supply of roots during winter.
Sow thinly along drills drawn out 300mm (12”) apart, and thin the seedlings when no more than 25mm (1”) high.
Aim for a final root spacing of 150mm (6”) along the rows.
Week 40: In preparation for the following season, manure the soil liberally with well-rotted compost, ensure the manure is dug in quite deeply or the roots may fork.
Week 43: If your ground is heavy or liable to deep frost penetration in winter, lift and store turnips sown before July.
Trim off turnip tops about 12mm (1/2”) above the crowns with a sharp knife.
Cover bottom of containers with moist sand, add alternate layers of roots and sand until filled.
Store under cover and inspect periodically for signs of rot.