RHS Growing Guides
How to grow kale
Our detailed growing guide will help you with each step in successfully growing Kale.
Getting Started
Enjoying a recent rise in popularity due to its superfood status, kale is easy to grow, good looking and productive, providing both mini salad leaves and tasty greens for cooking or adding to smoothies. It’s particularly valuable in winter, providing fresh leaves in even the coldest weather.
Kale Redbor
Kale Reflex
It forms large, attractive plants up to 90cm (3ft) tall, although dwarf varieties are also available for smaller spaces. Plants can be highly ornamental too, so needn’t be confined to the veg plot, with varieties offering a choice of smooth, ruffled or frilly green or purple-red leaves, sometimes with purple veins or stems.
You can use kale either as a
Month by Month
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Choosing
There is a wide choice of attractive and tasty kale varieties, offering a choice of smooth, ruffled or densely frilly leaves, long and narrow, or broad, or deeply divided, in various shades of green through to dark purple-red. The most well-known is ‘Cavolo Nero’ or ‘Black Tuscan’, but there are many other excellent varieties to bring interest to your veg plot, borders and dinner plate.
For the most reliable varieties, look for those with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg.
What and where to buy
Kale seeds are widely available in garden centres and from online seed suppliers. Young plants may also be available in spring and early summer, from the same sources.
Recommended Varieties
A popular Italian variety with dark green puckered leaves. Good strong flavour, full of iron. Harvest as cut-and-come-again....
Densely curled, branching stems with deep green leaves. Very hardy. Grows to 75cm (30in) tall.
With attractive vibrant purple leaves, it’s a colourful addition to veg plots and borders. Fully hardy, and tastes...
Preparing the Ground
Kale prefers rich, well-drained, firm soil, but will grow in most soil types and conditions. It likes sun, but will also tolerate light shade.
Weed the ground thoroughly and dig in plenty of well-rotted manure or garden compost. Then rake the soil level and firm it well.
Sowing
Kale Cavolo Nero
Kale Starbor
Kale can also be started off indoors, then transplanted straight into its final growing position.
Most varieties of kale grow into large plants, so need plenty of ground space. However, there are some dwarf varieties that are more compact. If grown as a salad crop, young plants can be kept small and need far less space than mature plants.
Sowing indoors
You can sow kale indoors in mid-spring, to get an early start. Fill a modular tray with multi-purpose compost, water well, then make a 1cm deep hole in each module. Sow two seeds in each, then cover with compost. If both germinate, remove the weaker seedling.
Transplant the young kale plants outdoors (see the transplanting section below), in early summer, after hardening off.
Sowing outdoors
Sow kale seeds outdoors from March to June, into prepared ground (see above). Spring sowings will provide harvests of leaves for cooking from autumn onwards, while early summer sowings provide winter and spring crops. Make sowings little and often for harvesting as mini salad leaves.
Draw out a shallow drill, 1cm (½in) deep, using a stick or the blade of a trowel, then water along the base if dry.
Sow the seeds thinly along the drill. If sowing more than one row, space them 15cm (6in) apart.
Once the seedlings germinate, thin them out initially to 7.5cm (3in) apart, removing the weaker ones. The thinnings can be used as baby leaves in salads.
Protect seedlings from slugs and snails, and birds if necessary - see the problem solving section below.
Young plants should be either transplanted to their final site in early summer, or thinned out further to 45cm (18in) apart, moving the spare plants to form new rows – see Transplanting, below. If growing as a cut-and-come-again salad crop, rather than growing to maturity, thinning isn’t usually necessary.
Transplanting
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Water the young kale plants well the day before moving
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Prepare your site as detailed above (see Preparing the ground). Be sure to firm the soil well, as kale can grow into large top-heavy plants that need to be well anchored in the soil, to stand up to winter gales
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Lift the young plants carefully, trying not to disturb the roots, then set them in their new planting hole, deep enough so their lowest leaves are at ground level
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Space plants 45cm (18in) apart and water generously to settle the roots in
Plants grown from seed indoors, and newly bought young plants, should be planted out using the above method in early summer, after hardening off.
Plant Care
Watering
Water kale regularly when young, until growing strongly. After that, plants should only need watering during dry weather.
Mulching
Apply a thick layer of mulch, such as well-rotted manure or garden compost, around the plants to help hold moisture in the soil and deter weeds.
Feeding
A spring feed of nitrogen-rich fertiliser will give overwintered plants a boost and improve harvests.
Weeding
Keep seedlings and young plants weed-free, to reduce competition for light, water and nutrients.
See our tips on controlling weeds.
Supporting
Tall varieties should be supported with a sturdy bamboo cane, especially in exposed sites. This will prevent winter gales buffeting these top-heavy plants and potentially loosening the roots.
Harvesting
Start to remove young leaves from the top of plants from September onwards.
Side-shoots develop after the main crown is harvested and these are ready for use in February and March. Pick shoots that are 10–15cm (4–6in) long and still young.
When growing as a cut and come again salad crop, start harvesting as soon as plants reach 10–15cm (4–6in) tall. Either pick individual leaves from several plants, or cut the whole rosette of leaves from a plant, in which case it should re-sprout to provide another crop.
Problems
Kale is generally very robust, hardy and trouble free. However, a few pests can cause problems, including slugs and snails, birds, whitefly and cabbage white butterflies.
Protecting from pests
Take care to protect seedlings and young plants from slugs and snails.
Birds and cabbage white caterpillars may also be a problem, in which case cover the plants with insect-proof mesh or fleece,, supported on a structure of bamboo canes.
As kale is a brassica, it is also susceptible to cabbage root fly, although less so than many other brassica crops. To deter them, you can place a felt cabbage collar around the base of the stems. These also help to prevent weed growth and some may also deter slugs and snails.
Get involved
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