How to Grow Swede
Brassica napus
Swede (rutabaga) prefers full sun, firm, fertile soil, and consistent moisture. Direct sow mid–late summer for autumn–winter harvests; earlier sowings risk bolting. Thin promptly and keep weed-free. Protect seedlings with mesh against flea beetle and pigeons; rotation helps avoid clubroot. Water during bulking to prevent woody texture. Harvest from tennis-ball to grapefruit size; flavour improves after frost. Lift as needed or store roots cool and damp. Leaves are edible when young; remove yellowing foliage to improve airflow.
When to Start
Direct sow outdoors as soon as soil reaches 5°C — typically early to mid spring. Hardy enough to tolerate light frosts.
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Growth Stages
Approximate days from start
Care Essentials
- Light balanced feed at sowing. Avoid high-nitrogen feeds.
- Slow-growing — sow in May/June for autumn/winter harvest. A brassica, so include in rotation.
Growing Conditions
- Min. soil temperature
- 5°C+
- Germination temperature
- 10–20°C
- Direct sow
- —
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Spacing & Planting
| Plant spacing | 20 cm |
| Row spacing | 40 cm |
| Sow depth | 1 cm |
| Mature height | 40 cm |
| Mature spread | 25 cm |
Also known as Rutabaga. Thin seedlings to this final spacing to allow for good root development.
Pests & Diseases
Pest Flea Beetle
Identification: Tiny round holes peppered across leaves (shot-hole damage); small, shiny black beetles that jump when disturbed; seedlings may be killed
- Cover rows with fine mesh or fleece immediately after sowing
- Keep soil moist — flea beetles prefer dry conditions
- Water seedlings in the evening to deter beetles
- Spray with pyrethrin-based insecticide in the evening when beetles are resting on leaves
Pest Cabbage Root Fly
Identification: Plants wilt despite adequate water; small white maggots found around roots; tunnels and brown scarring on root surface
- Cover rows with fine mesh or enviromesh to prevent egg-laying
- Use brassica collars around stems at soil level
- Rotate brassica crops on a 3-year cycle
- No effective chemical treatments available to home gardeners; prevention with barriers is the main approach
Pest Mealy Cabbage Aphid
Identification: Dense clusters of grey-white, waxy-coated aphids on leaf undersides; leaves curl and yellow; plants may be stunted
- Blast off with a strong jet of water
- Spray with insecticidal soap
- Encourage ladybirds and parasitic wasps
- Spray with a contact insecticide containing pyrethrins
Disease Clubroot Plasmodiophora brassicae
Symptoms: Swollen, distorted roots; stunted growth; leaves wilt in warm weather but may recover overnight; yellowing foliage
Treatment: No cure once soil is infected — remove and destroy affected plants; do not compost
Prevention: Lime acidic soils to raise pH above 7.0; rotate brassica crops on a 4+ year cycle; improve drainage; start plants in modules with clean compost; choose resistant varieties like 'Marian'
Disease Powdery Mildew Erysiphe cruciferarum
Symptoms: White, powdery coating on leaves; leaves yellow and die back; reduced root development
Treatment: Remove badly affected leaves; spray with a sulphur-based fungicide
Prevention: Space plants for good airflow; water at the base; avoid overhead watering; choose resistant varieties
Disease Brown Heart (Boron Deficiency)
Symptoms: Brown, corky patches inside the root flesh; may not be visible externally; roots taste bitter and have poor texture
Treatment: Apply borax at 35g per 20 square metres dissolved in water; do not exceed recommended rates
Prevention: Maintain soil pH between 6.5 and 7.0; add well-rotted compost; avoid overliming which locks out boron
Growing Conditions
| Min. soil temperature | 5°C |
| Germination temperature | 10–20°C |
| Base growth temperature | 4°C |
| Min. daylength to start | 8.5h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Swede?
- Plant Swede 20cm apart with 40cm between rows.
- Is Swede frost hardy?
- Swede is classified as Hardy.
