Collard greens

Sun

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

Water

Keep soil evenly moist, providing about 1-1.5 in (25-38 mm) of water weekly from rain and irrigation; water more often during hot, dry weather.

Soil

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

Height

2-4 ft (0.6-1.2 m)

Spread

1.5-3 ft (0.45-0.9 m)

Foliage

Large, waxy green to blue-green leaves with pale veins, forming an open rosette rather than a tight cabbage head.

Growth

Fast; many varieties reach picking size about 60-85 days after transplanting.

Care needed

Medium

• Heat tolerant
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.5 ft (0.15 m)

2. After 1 year

   3 ft (0.9 m)

   full size

Full size in one season.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the UK

Growth rate

Fast

• Space plants 18-24 in (45-60 cm) apart to allow good airflow and room for picking.
• Water at soil level and avoid repeated drying out, which makes leaves tougher.
• Work compost into the bed before planting; apply a nitrogen-containing vegetable feed during active growth according to its label.
• Mulch with compost or clean straw to conserve moisture, keeping it away from the stems.
• Cover young plants with insect mesh, sealing the edges against cabbage butterflies and other pests.
• Stake tall plants if wind or repeated harvesting leaves them top-heavy.

Pruning. No routine pruning is needed beyond harvesting. Remove yellowing or diseased lower leaves promptly, and remove flower shoots if you want to prolong leaf picking, although bolting usually signals declining crop quality.

Pick outer leaves once they are about 8-12 in (20-30 cm) long, while still tender and before they become yellow or leathery. Snap or cut leaves close to the stem, leaving the central growing point and several young leaves to keep producing; smaller leaves can be picked earlier.

Late winter

For a spring crop, sow indoors about 4-6 weeks before your last expected frost.

Spring

Harden off seedlings and transplant when the soil is workable; cover with insect mesh.

Early summer

Pick outer leaves regularly, maintain moisture and feed if growth slows.

Mid to late summer

Sow an autumn crop about 10-12 weeks before the first expected frost; shade and water seedlings during heat.

Autumn

Harvest through cool weather and use fleece or a low tunnel to extend picking.

Winter

In mild climates, continue harvesting sound leaves; where plants are killed by cold, remove residues and compost only healthy material.

• Plant in orderly rows in a kitchen garden for repeated leaf harvests.
• Use the broad blue-green leaves as a bold backdrop to parsley, lettuce and low-growing herbs in a potager.
• Mix into edible borders where upright stems and large leaves provide structure through autumn.
• Grow a single plant in a large container near the kitchen, allowing room for its mature spread.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Homestead, Farmhouse, Southern and Autumn colour.

Plant it with: Lettuce, Spinach, Onions, Beetroot, Dill and Sweet alyssum.

Wildlife: Leaves feed cabbage butterfly and moth caterpillars. If allowed to flower in their second year, the yellow flowers provide food for bees and other insects.

• Cabbage caterpillars chew holes and leave droppings: use well-sealed insect mesh, inspect leaf undersides and hand-pick caterpillars.
• Flea beetles make numerous small holes, especially in seedlings: protect young plants with fine insect mesh and keep them growing steadily.
• Cabbage aphids form grey, waxy colonies on young leaves: wash off small colonies and remove badly infested leaves; use an approved insecticidal soap if necessary.
• Clubroot causes swollen roots, wilting and poor growth: remove affected plants, improve drainage, avoid moving contaminated soil and keep brassicas out of the bed for several years.

The leaves and stems are edible and are not known to be toxic to people, cats or dogs in ordinary food amounts, though large servings may cause digestive upset. Do not use collards as substantial horse feed: large quantities of brassicas can cause digestive and other health problems.

• Kale (Brassica oleracea var. sabellica)

  Many kales have strongly curled, frilled or narrow leaves; collards usually have broader, flatter leaves. Smooth-leaved kales can be difficult to distinguish without knowing the variety.

• Cabbage (Brassica oleracea var. capitata)

  Cabbage develops a firm central head of overlapping leaves, while collards remain open and leafy.

• Swiss chard (Beta vulgaris subsp. vulgaris)

  Chard has conspicuous fleshy leaf stalks, often white, yellow or red, and usually glossier leaves; collards have waxier leaves on an upright cabbage-like stem.

Collard comes from the older word colewort, meaning a cabbage plant, while the Latin viridis means green.

Propagation. Grow from seed, sown about 0.25-0.5 in (6-12 mm) deep in modules or directly into prepared soil. Saved seed may not come true because collards cross readily with other flowering Brassica oleracea crops.

Accepted botanical name

Brassica oleracea Brassica oleracea var. viridis is an older name for 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.