Mustard greens

Sun

Full sun in cool weather; light afternoon shade can help in warmer conditions.

Water

Keep soil evenly moist but not waterlogged. Dry spells make leaves tougher and encourage early flowering.

Soil

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

Height

1-2 ft (0.3-0.6 m) in leaf; flowering stems can reach 3-5 ft (0.9-1.5 m)

Spread

1-2 ft (0.3-0.6 m), depending on variety

Foliage

Broad or finely divided leaves, smooth to heavily curled, in green, reddish purple or purple with green veins; flavour ranges from mildly peppery to hot.

Growth

Fast; baby leaves are often ready in 3-4 weeks.

Care needed

Low

• Low allergen
• Edible

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

Difficulty

Easy

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

   1.5 ft (0.45 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

Mildly toxic: may upset a stomach

Growth rate

Fast

• Water at soil level whenever the surface begins to dry; do not let seedlings dry out.
• Mix mature compost into the bed before sowing.
• Thin plants to 6-12 in (15-30 cm) apart for full-sized leaves, following the variety's spacing guidance.
• Apply a thin mulch once seedlings are established to conserve moisture and reduce soil splash.
• Use insect mesh from sowing to keep flea beetles and cabbage butterflies off the crop.
• Rotate with non-brassica crops and remove old roots after harvest.

Pruning. No routine pruning is needed. Remove yellowing leaves and harvest regularly; once flower stems develop, replace plants unless you want flowers or seed.

Cut baby leaves when they are about 3-6 in (8-15 cm) long, often 20-30 days after sowing. For larger leaves, usually ready in 40-60 days, pick the outer leaves while leaving the central growing point intact. Harvest before leaves become tough or plants begin flowering, when flavour usually becomes stronger.

Early spring

Sow directly once the soil is workable; use a cloche or fleece where hard frosts remain likely.

Mid-spring

Thin seedlings, cover with insect mesh and begin picking baby leaves.

Late spring

Make a final spring sowing where summers are cool; remove plants that bolt.

Late summer

Sow the main autumn crop and keep the seedbed moist during germination.

Autumn

Harvest outer leaves regularly and protect crops from hard frost.

Winter

Continue harvesting in mild climates or under protection; clear frost-killed plants in colder areas.

• Plant purple-leaved varieties beside green lettuce for contrasting blocks of edible foliage.
• Use frilled varieties along vegetable-bed edges where their texture is easy to see and harvest.
• Grow compact varieties in deep containers near the kitchen, alongside spring onions.
• Plant in orderly rows or repeated patches in a potager for quick seasonal colour and structure.

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

Plant it with: Lettuce, Spring onions, Beetroot, Carrots, Coriander and Calendula.

Wildlife: If allowed to flower, the yellow blooms provide nectar and pollen for bees and other insects. Leaves also feed cabbage-family caterpillars, so flowering plants are best kept separate from protected eating crops.

• Flea beetles leave small shot holes in young leaves: cover immediately after sowing with fine insect mesh, sealing the edges.
• Cabbage caterpillars chew large holes: inspect leaf undersides, remove eggs and caterpillars, and use insect mesh.
• Clubroot causes swollen roots and wilting: remove infected plants, improve drainage and avoid growing brassicas in affected soil; containers with clean compost are an alternative.
• Early bolting produces tough, strongly flavoured leaves: sow in cool seasons, water consistently and replace plants once flowering begins.

Leaves are edible for people in normal food quantities; mustard seed can cause serious reactions in people with mustard allergy. Small amounts of leaf are not generally considered poisonous to cats or dogs, but larger amounts and pungent seeds may cause digestive upset. Do not use it as unrestricted horse forage: heavy consumption of brassicas can cause serious digestive or blood disorders, and stressed plants may accumulate nitrates.

• Black mustard (Brassica nigra)

  Mature black mustard has short seed pods held tightly against the flowering stem; brown mustard generally has longer pods that project away from it. Leaves alone can be difficult to distinguish.

• White mustard (Sinapis alba)

  White mustard is usually noticeably hairy and develops bristly seed pods with a broad, flattened beak; brown mustard pods are smooth and more slender.

• Pak choi (Brassica rapa subsp. chinensis)

  Pak choi usually forms a compact rosette with broad, fleshy white or pale green leaf stalks and mild leaves. Most mustard greens have thinner stalks and a distinctly peppery flavour, though leaf forms overlap.

The species name juncea means rush-like, referring to the slender growth of the plant.

Propagation. Sow seed directly about 1/4 in (0.5 cm) deep in cool, moist soil. Sow small batches every 2-3 weeks during suitable weather; plants can self-seed if pods are allowed to ripen.

Accepted botanical name

Brassica juncea

In the US and Canada

Introduced in Alaska, Canada, Hawaii, the lower 48 states, Puerto Rico and US Virgin Islands.

Native range

North Caucasus and Transcaucasus.

Measured

Soil pH 6 to 7.2. Average height 110 cm.

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