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Swedes

This Allotment Pro editorial draft summarises the cited RHS guide. Check the source and adjust timings for local conditions.
RHS source guide
Swede crop illustration

Month by month

Sow

  1. Late spring to early summer

    direct-sow outdoors in prepared ground.

  2. Mid-spring

    start individual seedlings in modules for an earlier crop.

Harvest

  1. Early autumn onward

    lift roots as soon as they reach the preferred size.

  2. Autumn through winter

    harvest as needed, protecting roots left in the ground from severe weather.

1

1 - Getting Started

Swedes are hardy brassica root vegetables harvested mainly during autumn and winter. They are closely related to turnips but usually have yellow flesh and a stronger, sweeter flavour. Regional names include Swedish turnip, turnip, neep and rutabaga.

Brassica napus Napobrassica Group forms a large rounded root or swollen stem, commonly dark purple above ground and creamy yellow below. Plants grow slowly and may take up to six months to mature. Roots can be lifted from early autumn when large enough, or protected and left in the ground until Christmas and beyond. Cooked flesh is creamy yellow with a sweet nutty flavour.

2

2 - Choosing What To Grow

Most cultivars produce rounded roots with purple tops, creamy bases and pale-yellow flesh. Check each seed packet because sowing times and winter-keeping ability vary. For a long harvest, choose a cultivar that resists woodiness and stores well. Resistance to club root or powdery mildew is particularly useful where those problems recur.

Recommended varieties

3

3 - Preparing The Ground

Choose an open sunny site with moist, fertile soil that drains freely. Incorporate plenty of garden compost or well-rotted manure, ideally well before sowing. Test acidic soil and apply lime only when the result shows it is needed; raising pH can reduce conditions favourable to club root.

Remove weeds and large stones, then firm the ground by treading with a shuffling action and rake the surface level. In a no-dig system, mulch with organic matter ahead of sowing and sow through that layer. Include swedes with other brassicas in the crop rotation to limit soil-borne disease and insect build-up.

4

4 - Sowing

Sowing outdoors

Direct sowing from late spring to early summer is the usual method. Make a shallow drill about 2cm (¾in) deep, water its base and sow thinly. Keep rows 38cm (15in) apart. Protect early sowings with cloches or plastic-free fleece and guard seedlings from slugs and snails.

Thin seedlings as soon as they can be handled, leaving 20–25cm (8–10in) between plants for full-sized roots. For baby swedes, reduce final spacing to 8–10cm (3–4in). Several small sowings a few weeks apart can extend the harvest.

Sowing in containers

Full-sized swedes are unsuited to pots, but baby roots can be grown in a warm sunny position. Use a container at least 40cm (16in) wide, fill with peat-free multi-purpose compost, water well and sow thinly. After germination, thin seedlings to 8–10cm (3–4in) apart and harvest them young.

Sowing indoors

For a head start, sow from mid-spring in modules of peat-free seed compost. Individual cells reduce root disturbance. Harden seedlings off carefully and transplant in early summer before they begin forming the main tap root, preventing a check to growth or malformed roots.

5

5 - Plant Care

Swedes occupy the ground for up to six months. Keep young crops weed-free and supply dependable moisture so roots swell evenly.

Watering

Water seedlings regularly until established. Thereafter keep soil evenly moist during dry spells. Container compost dries particularly quickly and needs frequent attention. Drought may split roots, make them bitter and encourage powdery mildew.

Mulching and weeding

Apply a thick layer of garden compost or well-rotted manure over the soil surface to hold moisture and suppress weeds. Mulching is especially valuable on light sandy ground. Weed throughout the season, taking care not to cut the root shoulders when hoeing.

Protecting the crop

As brassicas, swedes are vulnerable to cabbage-family insects and diseases. Choose resistant cultivars where appropriate and cover plants with properly secured insect-proof mesh. Rotate the crop and inspect foliage and roots regularly.

6

6 - Harvesting

Harvest at the size preferred: baby roots after a few weeks, young roots around 5cm (2in) across, or the usual mature size of 10–15cm (4–6in). Larger roots remain tender only in cultivars selected not to turn woody.

Main crops are ready from early autumn and can remain in the soil into winter. Before severe weather, cover the bed with straw, cloches or plastic-free fleece. In cold districts or wet winter soil, lift roots in late autumn and pack them in moist sand or peat-free potting compost in a frost-free shed or garage.

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7 - Problem Solving

Steady moisture is central to healthy root development. Drought can cause splitting and bitterness, while dry-stressed foliage is prone to powdery mildew. Crop rotation, pH management, mesh and prompt identification help manage the wider range of brassica problems.

Common problems

Club root

This soil-borne brassica disease produces swollen distorted roots and weak top growth. Rotate crops, improve drainage and correct excessive acidity where a soil test supports liming.

Problem source

Cabbage caterpillars

Several butterfly and moth caterpillars feed on brassica foliage. Inspect leaf undersides and use insect-proof mesh before eggs are laid.

Problem source

Cabbage root fly

White maggots feed on brassica roots and can tunnel into swedes. Fine mesh prevents adult flies reaching the crop.

Problem source

Flea beetles

Small beetles make numerous shot holes in young brassica leaves. Keep seedlings growing steadily and protect vulnerable sowings with mesh.

Problem source

Powdery mildews

White dusty fungal growth develops on foliage, especially when roots are dry. Maintain soil moisture, spacing and airflow and choose resistant cultivars where useful.

Problem source

White blister

This foliar disease can reduce vigour and distort infected brassica growth. Remove badly affected material and rotate crops.

Problem source

Pigeons

Pigeons tear brassica leaves and may leave only stalks and major veins. Secure wildlife-safe netting so birds cannot reach or become trapped in it.

Problem source

Slugs and snails

Young plants are especially vulnerable in damp conditions. Inspect hiding places and combine physical protection with wildlife-friendly controls.

Problem source