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Turnip

Ready in six weeks, so it fills gaps in a bed better than almost anything else.

1. Sow direct where they will grow, turnips resent transplanting.
2. Draw a drill 1.5 cm deep and sow 2 seeds every 5 cm.
3. Thin to 10 cm apart when the seedlings have two true leaves, and eat the thinnings as greens.
4. Keep the soil evenly damp from the day you sow.
5. Sow a new short row every 3 weeks from spring to late summer.
6. Pull at golf-ball to tennis-ball size, 6 to 8 weeks after sowing.
7. In mild zones leave the autumn sowing in the ground and pull through winter.

Soil

Light soil with no fresh manure, pH 6.5 to 7.0. Stones cause forking.

Sun

Full sun in cool weather, light shade in warm weather.

Water

15 to 20 mm a week, evenly. Dry then wet gives split, woody roots.

Spacing

Thin to 10 cm apart, rows 30 cm

Depth

1.5 cm deep

Care

['Hoe weeds while the seedlings are small, they cannot compete.', 'No feed is needed, nitrogen just makes leaf.', 'Skip midsummer sowings in Mediterranean and arid zones, heat makes them bolt and taste hot.', 'Harvest the leaves too, turnip tops cook like spring greens.']

Harvesting

Pull at 5 to 8 cm across. Anything bigger goes woody and pithy in most varieties. Twist off the tops immediately so they do not draw moisture out of the root.

Storing

2 to 3 weeks in the fridge in a bag, or 3 months in damp sand in a cool shed at 2 to 4 C. Winter varieties keep longest.

Grow it next to

Peas, beans and mint. Keep away from other brassicas to spread the pest risk.

Problems

[{'cause': 'Grown too slowly in heat or drought, or left too long', 'fix': 'Sow in cool weather, water steadily, pull at 6 cm.', 'symptom': 'Roots hot and woody instead of sweet'}, {'cause': 'Flea beetle, worst in dry spring weather', 'fix': 'Cover with fine mesh from sowing and keep the soil surface damp.', 'symptom': 'Seedlings peppered with tiny round holes'}, {'cause': 'Clubroot, a brassica soil disease', 'fix': 'Lime to pH 7.0, never grow brassicas in that bed for 7 years, and grow in pots meanwhile.', 'symptom': 'Roots swollen, lumpy and rotting'}, {'cause': 'Cabbage root fly maggots', 'fix': 'Mesh the row or fit 12 cm collars around the stems.', 'symptom': 'Tunnels through the root'}]

Saving your own seed

Biennial. Overwinter a few roots, let them flower in year two. It crosses freely with Chinese cabbage and other turnips, so isolate by 400 m.

Containers

Good in a pot at least 25 cm deep. Sow a band and thin to 10 cm. Baby turnips do especially well this way.