Kale is a good crop for people who want fresh greens beyond the height of summer. Unlike heat-loving vegetables, many kale varieties grow well in cooler conditions, and established plants can supply leaves over a long period. Getting them started is straightforward, but the timing matters if you don't want seedlings struggling in hot dry weather.
You can sow kale in modules and transplant it, or sow directly into prepared ground. The important details are even depth, enough room between plants and protecting young leaves from pests.
Pick a kale variety
Curly green kale, red Russian types and dark Tuscan or cavolo nero kale have different leaf shapes and growing habits.
The Royal Horticultural Society recommends choosing varieties based on the harvest you want and your growing conditions. Some are more attractive as winter greens, while others suit younger salad leaves.
Read the seed packet for height, spread and sowing window. A compact variety for small leaves may need different spacing from a tall plant intended for repeated harvest.
Know when to sow in Britain
Kale is commonly sown from spring into early summer, depending on the variety and intended harvesting season. The RHS provides specific regional guidance.
Starting under cover can protect the earliest seedlings from harsh weather. Later outdoor sowing may be straightforward once the soil is workable.
Don't sow every seed in one week. A few staggered sowings can provide plants of different ages and reduce the chance of an enormous glut.
Choose a suitable position
Kale generally performs well in fertile moisture-retentive soil with good drainage. Full sun is useful, though some varieties tolerate light shade.
Prepare the ground by removing weeds and incorporating suitable organic matter where soil structure needs improvement.
Avoid a patch that stays waterlogged. Healthy brassica roots need both moisture and air, especially during cool months.
Decide between modules and direct sowing
Modules let you raise seedlings in controlled conditions and plant them out once stronger. This can help avoid some early slug damage.
Direct sowing saves transplanting and can work well in a prepared bed. However, thinning becomes important because seeds often germinate in clusters.
Both methods are valid. Choose based on the season, your available space and how much pest pressure your garden experiences.
Sow at the recommended depth
Kale seeds are small. The RHS advises sowing roughly 1cm deep for many brassica vegetables, but follow the actual packet.
Sow one or two seeds per module, or place seeds at regular intervals along a shallow drill outdoors. Cover gently with fine compost or soil.
Water using a fine rose to avoid washing the seeds into a heap. Label the row so you can identify the seedlings when weeds appear.
Give seedlings enough light
Germinating kale benefits from consistent moisture. Once sprouts emerge, provide bright light and avoid keeping them too warm indoors.
Seedlings on a gloomy windowsill can develop long weak stems. Moving them into suitable sheltered bright conditions usually gives stockier growth.
Check daily but avoid watering automatically. The compost should not remain soaked indefinitely.
Thin and transplant carefully
If two or three seedlings emerge in a module, keep the healthiest or carefully separate them when appropriate. Do not yank roots through one another.
Harden indoor seedlings off gradually before planting out. The change in sun, wind and temperature can otherwise cause damage.
Lift by the root ball, set at the recommended depth and water in gently. Protect from strong sun for the first few days if conditions are unusually hot.
Leave room for mature plants
Large kale varieties may need around 45cm between plants, though spacing varies with type and whether you harvest baby leaves.
Crowding can create smaller plants and reduced airflow. A dense mass of leaves is also harder to inspect for caterpillars or aphids.
If growing for young leaves, closer sowing and more frequent cutting may suit the method. Follow the variety guidance.
Protect against pigeons
Pigeons can strip young brassicas, especially when other food is scarce. Suitable netting or mesh can protect seedlings from serious damage.
Use supports so netting doesn't sag onto the leaves, and secure the edges to prevent birds becoming trapped.
Check protective structures regularly. Netting that is poorly fitted can harm wildlife and make garden maintenance difficult.
Watch for cabbage white caterpillars
Kale is a brassica, so cabbage white butterflies may lay eggs on it. Caterpillars can quickly chew holes through young leaves.
Inspect the undersides of leaves and use suitable fine insect mesh if needed. Check for pests before covering plants, otherwise you may trap them inside.
Avoid unnecessary broad-spectrum sprays. Physical barriers and regular inspection often make more sense in a small kitchen garden.
Water in dry spells
Kale prefers steady moisture while establishing. Water the base of plants thoroughly in dry weather, especially in containers.
Avoid keeping soil permanently saturated. A wet root zone can cause problems even when the leaves appear thirsty from heat.
Mulching appropriately can help retain moisture and reduce weeds, provided it isn't piled against the plant stems.
Feed only as needed
A reasonably fertile bed may support good kale without heavy supplementary feeding. Pale slow-growing leaves can have several causes, including soil and pest problems.
Use soil improvement or fertiliser according to RHS guidance and product instructions. Excess feed is not an automatic cure for poor light or crowded roots.
Remove weeds regularly so kale isn't competing for water and nutrients.
Harvest outer leaves gradually
Once plants are established, pick suitable older outer leaves while leaving the central growing point intact. This allows many varieties to produce new growth.
Avoid stripping a very young plant bare. It needs leaves to continue growing and recover after picking.
For a one-time harvest, you can cut a larger batch when the plant is mature enough. Choose the method to match your cooking plans.
Kale in winter
Many kale types tolerate cool weather and some frost, making them useful when other crops have finished.
Growth slows in short winter days, so don't expect leaves to be replaced as quickly as in spring or summer.
Protect plants from severe weather where needed and check for pests and rot under dense foliage.
Common mistakes
Sowing too densely, forgetting pest protection and allowing seedlings to dry out are common problems.
Another is expecting mature tall kale plants from baby-leaf spacing without thinning. Decide which harvest you're growing.
A straightforward first bed
Sow a few labelled modules in season, grow seedlings in good light, harden off, and transplant to fertile soil with adequate space.
Protect them from pigeons and caterpillars, then harvest the outer leaves little and often. Kale is a practical crop when you plan for its needs rather than treating it as a generic salad green.