Kale

Sun

Full sun; light afternoon shade is useful in hot climates.

Water

Keep the root zone evenly moist, providing about 1-1.5 in (2.5-4 cm) of water weekly, including rain. Containers may need watering daily in warm weather.

Soil

Fertile, moisture-retentive but well-drained soil, ideally pH 6.0-7.5.

Height

1-3 ft (0.3-0.9 m), depending on cultivar

Spread

1-2 ft (0.3-0.6 m)

Foliage

Broad, edible leaves that may be tightly curled, frilled or long and puckered, in green, blue-green or purple. Plants can remain leafy through mild winters.

Growth

Fast in cool weather

Care needed

Medium

• Mix mature compost into the soil before planting and space most cultivars 12-24 in (30-60 cm) apart.
• Water at soil level before the soil dries out; drought makes leaves tougher and slows growth.
• Mulch with 2 in (5 cm) of compost or clean straw, keeping it clear of the stems.
• Apply a nitrogen-containing vegetable fertiliser according to its label if growth slows or older leaves become pale.
• Use insect-proof mesh from planting, with edges secured, to exclude cabbage butterflies and moths.
• Support tall plants with a short stake in exposed gardens.

Pruning. Harvest the lower, outer leaves once plants are established, leaving the central growing point and several healthy leaves intact. Remove yellowing leaves promptly and pull plants when they become unproductive or start flowering, unless you want flowers or seed.

Early spring

In cool climates, sow under cover about 4-6 weeks before your usual last frost.

Spring

Harden off seedlings and transplant into prepared soil; cover with insect-proof mesh.

Summer

Water consistently, check leaf undersides for pests and harvest outer leaves regularly.

Late summer

Sow or transplant a second crop for autumn and winter harvests, allowing enough growing time before cold weather slows growth.

Autumn

In mild-winter and hot-summer regions, establish kale as a cool-season crop; stake tall plants before winter winds.

Winter

Harvest surviving plants lightly, let frozen leaves thaw before picking and use fleece or a cold frame where needed.

• Plant repeated rows in a potager for a strong foliage pattern and a continuing edible harvest.
• Use purple or blue-green cultivars among calendulas and nasturtiums for contrasting colour and texture.
• Grow compact cultivars in large patio containers close to the kitchen.
• Place taller, puckered-leaved forms behind parsley and lettuces in an edible border.
• Use cold-tolerant cultivars to keep vegetable beds leafy into autumn and mild winters.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Cottage garden, Homestead, Autumn colour and Small-space.

Plant it with: Lettuce, Parsley, Chives, Calendula, Nasturtium and Sweet alyssum.

Wildlife: Leaves feed cabbage butterfly and moth caterpillars. If allowed to flower in its second year, the yellow flowers provide food for bees and other insects; mesh used to protect the crop also excludes these visitors.

• Cabbage caterpillars: protect young plants with insect-proof mesh, inspect leaf undersides and hand-pick caterpillars and eggs.
• Aphids: check curled leaves and growing tips; wash colonies off with water or use insecticidal soap labelled for edible crops.
• Clubroot: swollen roots and wilting indicate infection; remove affected plants, improve drainage and avoid brassicas in infected ground for several years. Use clean transplants and resistant cultivars where available.
• Poor growth and tough leaves in heat or drought: water consistently, mulch and shift the main crop to cooler months.

Leaves and stems are edible and are not known to be toxic to people, cats or dogs in ordinary food amounts, although large servings may cause digestive upset. Kale is not suitable as unrestricted horse feed: large amounts of brassica foliage can cause serious digestive, blood or thyroid problems in livestock.

• Collard greens (Brassica oleracea, Collard Group)

  Collards usually have broad, relatively smooth leaves on an upright stem; many kales have curled or strongly puckered leaves. Smooth-leaved kale and collards can overlap in appearance.

• Ornamental cabbage (Brassica oleracea)

  Ornamental forms commonly make low, dense rosettes with pink, white or purple centres. Ornamental kale belongs to the same species, so appearance alone does not establish whether a nursery plant was grown for eating.

• Mustard greens (Brassica juncea)

  Mustard greens often have thinner, more toothed leaves and a distinctly hot mustard flavour; kale generally has thicker leaves and a cabbage-like flavour.

Kale is a Scots form of cole, an old word for cabbage ultimately derived from the Latin caulis, meaning stalk or cabbage.

Propagation. Grow from seed, sown about 0.5 in (1 cm) deep in modules or directly into prepared soil. Kale cross-pollinates with other flowering Brassica oleracea crops, so saved seed may not come true to type.

Accepted botanical name

Brassica oleracea

In the US and Canada

Introduced in the lower 48 states, Pacific Basin and Puerto Rico.

Native range

France, Great Britain and Spain.

Measured

Soil pH 7 to 7.5. Average height 50 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.