Brassica root
How to grow swedes
Brassica napus (Napobrassica group)
Swede is the slow, hardy winter root of the brassica family: one sowing, five months in the ground, and roots that stand outside through frost. Sow direct in May or early June into firm, fertile soil in full sun, thin in stages to 23 cm and lift from October. Choose a variety with clubroot and mildew resistance, and keep the soil moist through August, because drought is what makes swedes woody.
- Hardiness
- Fully hardy
- Position
- Full sun
- Soil
- Firm, fertile, moisture-retentive
- Ideal pH
- 6.5 to 7.0
- Water
- Moderate, dry spells make roots woody and split when rain returns
- Feeding
- Moderate feeder
Sowing and planting swedes
WhenSow May to Jun direct; harvest Oct to Feb
Starting off
Direct only, in May to mid June, into firm, limed soil, germinating in 7 to 10 days at 10 to 20 °C; earlier sowings in cold soil bolt and later ones stay small. Cover with mesh from day one.
Spacing and planting
Sow 2 cm deep in drills 38 to 45 cm apart and thin in stages to 23 to 25 cm apart, which gives roots of 1 kg or more. Not a container plant; the roots need open, firm ground for 5 months.
Varieties worth growing
- Marian
- Purple-topped, yellow-fleshed and resistant to both clubroot and powdery mildew. The standard garden swede.
- Invitation
- Very hardy, with clubroot and mildew resistance; the one to leave in the ground until February.
- Gowrie
- Scottish-bred, purple-skinned and uniform, with good resistance to clubroot and mildew.
- Best of All
- Old favourite with mild, fine-textured yellow flesh. Hardy, but has no clubroot resistance, so only for clean ground.
- Tweed F1
- Vigorous hybrid giving even, round roots with sweet flesh; good where you want a row that all sizes up together.
Swedes month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Lift roots as needed. Cover the row with straw if a long hard frost is forecast.
- February
Lift the last roots before they start back into growth. Test the soil pH on next year's bed and lime if it is below 6.5.
- March
Nothing to do on the crop. Let limed ground settle.
- April
Fork over lightly, then tread and rake the bed firm. Rake in the base dressing at the end of the month.
- May
Sow thinly, 2 cm deep, in rows 38 to 45 cm apart. Mesh over at once.
- June
Finish sowing by mid June. Start thinning when the seedlings have two true leaves.
- July
Final thinning to 23 to 25 cm. Top-dress once. Water in dry spells.
- August
Water thoroughly every 10 days in drought. Mulch. Watch for mildew.
- September
Keep weeded. Remove yellowing lower leaves.
- October
Start lifting when the roots reach 10 to 15 cm across. Net against pigeons.
- November
On heavy or wet soil lift the crop and store in damp sand. On light soil leave it in.
- December
Lift as needed. Flavour is at its best after frost.
Feeding swedes
A moderate feeder that wants firm soil, the right pH and trace boron more than it wants nitrogen. One base dressing and one top-dressing is the whole plan; heavy feeding gives soft roots that do not keep.
As a brassica it appreciates lime and steady feeding, but avoid excess nitrogen, which softens the roots.
Feeding plan
Late winter, only if a pH test reads below 6.5
Garden Lime (calcium carbonate)
About 0.5 kg/m², at least two months before sowing. Do not lime without a test.
Late April, a week or two before sowing
Fruit & Vegetable Fertiliser 4-5-6
70 g/m², the bottom of the label range, raked into the surface. For rows 40 cm apart that is about 30 g per metre of row.
At sowing, on light or recently limed soil
1 to 2 g/m², a quarter to half a level teaspoon per square metre, scattered evenly, once. Never more: boron is toxic in excess.
July, after the final thinning
Fruit & Vegetable Fertiliser 4-5-6
50 g/m² between the rows, about 20 g per metre of row, hoed in and watered. That brings the season to 120 g/m², inside the 150 g/m² label limit.
Every 2 to 3 weeks, July to September
1 g per litre of water over the leaves and soil; optional, and most useful on sandy ground.
Signs to watch
Brown, water-soaked patches in the flesh with no outward sign
Boron short on limed, light soil
Borax at 1 g per square metre or regular seaweed feeds
Woody, split roots
A dry spell followed by rain, not a nutrient fault
Mulch and water steadily
Lush tops, small roots
Excess nitrogen
One balanced top-dress only
Pests, diseases and problems
Plants wilt on warm days, leaves turn purplish, roots are swollen, knobbly and foul-smelling
Clubroot, a soil-borne disease that persists for 20 years and is worst on acid, wet soil
Lime to pH 7 or a little above if a test shows the soil is acid, improve drainage, keep a four-year gap between brassicas and grow Marian, Invitation or Gowrie.
White powdery coating on the leaves in late summer
Powdery mildew, almost routine on swede after a dry August
Water thoroughly in dry spells and mulch between the rows. Grow resistant varieties. A late attack in September costs little.
Seedlings wilt and die; older roots tunnelled by white maggots
Cabbage root fly
Cover with fine insect mesh from the day of sowing, edges buried, and leave it on until autumn.
Small round holes all over the seedling leaves
Flea beetle, most damaging on a May sowing in dry weather
The same mesh keeps most of them out. Water the drill before sowing and keep the seedlings growing fast.
Grey, waxy clusters of insects under the leaves, leaves puckered and yellow
Mealy cabbage aphid
Squash small colonies by hand or wash them off with a jet of water. Mesh keeps the winged adults off.
Leaves stripped to the midrib in winter
Wood pigeons
Net the row from October, held clear of the leaves on hoops.
Harvest and rotation
Harvest and storage
Lift from October when roots are 10 to 15 cm across, 20 to 26 weeks from sowing; flavour improves after frost. Loosen with a fork and twist off the leaves. A 3 m row yields 8 to 10 roots of 1 to 1.5 kg. Leave in the ground until February on well-drained soil, or lift in November and store in damp sand in a cool shed.
Rotation and companions
Rotation: brassica group, 4-year gap; follows peas and beans well on their nitrogen and limed ground. Peas or dwarf beans nearby add nitrogen without shading.
Good to knowKeep evenly watered for tender roots; liming helps guard.
Growing swedes in pots
Swede is not a container crop. Each root needs about 23 cm of space and five months in firm, open ground, and compost in a pot is too loose and dries too fast to give a good root. If you only have pots, grow turnips or kohlrabi, which do the same job in a fraction of the time.
Swedes: common questions
When should I sow swede seeds?
Sow direct outdoors from early May to mid June. In the north and Scotland the first half of May is best; in the south, late May or early June reduces mildew. Earlier sowings into cold soil tend to bolt, and anything sown after June makes small roots.
What is the difference between a swede and a turnip?
A swede is larger, slower and hardier, with yellow flesh and a neck at the top of the root; a turnip is smaller, usually white-fleshed and ready in 6 to 10 weeks. Swede is sown once in late spring for winter use and stands through frost. Turnips are sown little and often from March to August and eaten young.
Why are my swedes small and woody?
Drought in summer, late sowing or crowding are the usual reasons. Swedes need steady moisture in July and August, 23 cm between plants and a sowing date before mid June. Loose, recently dug soil also gives poor roots, so firm the bed well before sowing.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.