Kale
Brassica oleracea var. sabellica
Kale is the hardiest of all brassicas, standing through the worst of British winters without flinching. Its reputation as a 'superfood' is well deserved — it's packed with vitamins, iron, and antioxidants. 'Nero di Toscana' (cavolo nero) produces long, dark, crinkled leaves that are superb in Italian dishes and stir-fries. 'Dwarf Green Curled' is the traditional British variety, compact and intensely flavoured. 'Red Russian' has pretty purple-veined leaves and is one of the tenderest varieties. Harvest by picking a few leaves from each plant rather than stripping it — the plant will keep producing new growth from the top. Kale's flavour improves markedly after frost, becoming sweeter and less bitter. It's one of the few crops you can sow from March right through to July and still get a useful harvest. Unlike other brassicas, its open habit means whitefly is less of a problem.
When to Sow Kale
Sow kale in March, April, May, June, July.
Time to Harvest Kale
Expect to harvest approximately 3 months after sowing, usually from September to April.
Companion Plants for Kale
- Maris Piper Potato
Early potatoes are lifted in midsummer, leaving firm, cleared ground that kale can be planted into for winter.
- Beetroot
Low beetroot can be grown between young kale plants and pulled before the kale spreads.
Expected Yield
Pick-and-come-again cropping; each plant provides several kg of leaves over winter.
Common Problems with Kale
Caterpillars
Cabbage white butterfly caterpillars can strip kale leaves to bare stalks within days. Cover plants with fine mesh netting immediately after planting and keep it in place from May to October. Check leaf undersides regularly for clusters of yellow eggs and squash or remove them before they hatch. Picking off individual caterpillars by hand is effective on a small scale.
Whitefly
Tiny white flies cluster on leaf undersides, particularly on overwintering kale, sucking sap and producing sticky honeydew. Blast off with a strong jet of water from the hose — this is surprisingly effective when repeated every few days. Yellow sticky traps hung among the plants help monitor and reduce numbers. Cold weather naturally reduces whitefly populations.
Aphids
Grey-green mealy aphids can build up on kale leaves, particularly in the sheltered heart of the plant where they're hard to spot. Wash off with a strong spray of water, or use a diluted washing-up liquid spray. Encouraging natural predators like ladybirds, hoverfly larvae, and lacewings is the best long-term solution — avoid broad-spectrum insecticides that kill these beneficial insects.
Kale: common questions
When should I sow kale in the UK?
Sow kale from March to July. Sow under cover for an early start, or directly outside once the soil has warmed.
How far apart should I plant kale?
Space kale about 45cm apart. It grows to around 60cm tall. Sow seeds 1–2cm deep.
How long does kale take to germinate?
Kale seeds usually germinate in 5–10 days, depending on temperature.
When is kale ready to harvest?
In the UK, kale is usually harvested from September to April. It's ready about 3 months after sowing.
Does kale come back every year?
No. Kale is a biennial that's grown for a single season: it's harvested in its first year, before it would flower, so sow it fresh each year.
What grows well with kale?
Good companions for kale include Maris Piper Potato and Beetroot. See the companion plants section above for why each one helps.
Is kale frost hardy?
Yes. Kale is hardy and survives a normal UK winter outdoors.
Is kale a brassica?
Yes. Kale belongs in the brassicas group for crop rotation. Grow it in a different bed each year, alongside other brassicas, so pests and diseases don't build up in the soil.
Kale guides
Plan your kale in the allotment planner
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