Mizuna is a Japanese leafy green with deeply cut, feathery leaves and thin white stems. Its flavour is mild and peppery, milder than most mustards. It grows fast, crops for weeks as a cut-and-come-again green, and tolerates cold well. It is one of the easiest greens you can grow, provided you give it cool weather.
Sowing and planting
Mizuna does best in the cool seasons at either end of the year. Aim to harvest before hot weather arrives, or after it has passed.
Spring crops. Sow outdoors from about four to six weeks before your last frost, as soon as you can work the soil. Seeds sprout in 4 to 10 days in cool soil. You can also start seed indoors five to six weeks before your last frost. Plant out after hardening off (getting seedlings used to outdoor sun, wind and cold) for about a week.
Autumn crops. Sow again from late summer, about six to eight weeks before your first frost. Autumn plants are often the best of the year. Shortening days and cooler nights keep them leafy and slow to flower. In hot areas, shade the seedbed with cloth until the seedlings establish.
Winter crops. In USDA zones 7 and warmer, autumn sowings often carry on through winter. In colder areas, grow mizuna under a cold frame, a low tunnel or an unheated greenhouse.
How to sow. Scatter seed thinly in rows 12 to 18 inches (30 to 45 cm) apart, or broadcast it across a wide band for baby leaves. Cover with 1/4 inch (6 mm) of fine soil and keep the surface moist. For full heads, thin seedlings to 8 to 12 inches (20 to 30 cm) apart. Eat the thinnings.
Succession sowing. Sow a short row every two to three weeks through spring and again through autumn. This gives you a steady supply of tender leaves while older plants slow down.
Mizuna also grows well in pots and window boxes at least 6 inches (15 cm) deep. Use a good potting mix and keep it moist.
Growing on
Watering. Keep the soil evenly moist. Dry soil makes the leaves tough and hot-tasting, and it pushes plants to flower. Water at the base, ideally in the morning.
Feeding. Mizuna is a leaf crop, so it likes nitrogen. Dig compost into the bed before sowing. Give cut-and-come-again plants a liquid feed of fish emulsion or seaweed every two to three weeks. Follow the label rates.
Mulching. Once seedlings are a few inches tall, lay a thin mulch of straw or shredded leaves between rows. Mulch keeps roots cool and moist, holds back weeds and keeps soil off the leaves.
Support and pruning. Mizuna needs no staking. Regular cutting is the only pruning it needs. Remove any flower stems as soon as they appear if you want to extend leaf harvests.
Protection. Cover young plants with insect netting or floating row cover (a light fabric laid over the plants). This keeps off flea beetles and cabbage butterflies, and it adds a few degrees of frost protection in autumn.
Companions. Mizuna fits between slower crops such as brassicas, onions and garlic, and it is ready before they need the space. Herbs such as dill and cilantro draw in insects that feed on aphids.
Mizuna bolts (runs to flower) quickly in heat and long days. Once it bolts, the leaves turn tough and hot-tasting. Sow for cool weather, keep the soil moist, and give it afternoon shade in warm spells.
Harvesting
Baby leaves. Start cutting when leaves are 3 to 4 inches (8 to 10 cm) long, about three to four weeks after sowing. Use scissors to cut the whole row about 1 inch (2.5 cm) above the soil. Leave the growing point intact. Plants regrow within a couple of weeks, giving you two to four more cuts.
Individual leaves. For a continuous supply, pick the outer leaves from each plant and let the centre keep growing.
Full heads. Cut the whole plant at the base when it forms a dense, fountain-shaped clump, 35 to 50 days after sowing.
Harvest in the cool of the morning, when leaves are crisp. Rinse, spin dry and store in a bag in the refrigerator for up to a week. Use young leaves raw in salads. Add larger leaves to stir-fries, soups and noodle dishes at the last minute. Mizuna also pickles well.
Light frost often sweetens the leaves. Pick before a hard freeze, or protect the plants.
Saving seed. Mizuna crosses readily with other Brassica rapa crops, including turnips, bok choy and Chinese cabbage. To save pure seed, let only one of these flower at a time. Allow a few healthy plants to bolt and set pods. Cut the stems when the pods turn tan and dry, then finish drying them in a paper bag. Rub out the seed and store it cool and dry.
Problems and pests
Leaves covered in tiny round holes
Flea beetles, small jumping black beetles, chew these "shot holes". Young plants suffer most in warm, dry weather. Cover seedlings with fine netting from sowing. Keep the soil moist, since flea beetles prefer dry conditions. Established plants usually outgrow the damage.
Large ragged holes and green caterpillars
Caterpillars of the cabbage white butterfly and cabbage looper feed on all brassicas. Check under the leaves and hand-pick them. Netting keeps butterflies from laying eggs. If numbers are high, spray Bacillus thuringiensis (Bt), a bacterial insecticide that targets caterpillars. Wear gloves and follow the label.
Sticky, curled leaves with grey clusters
Cabbage aphids (small sap-sucking insects) gather in the crown and under leaves. Wash them off with a strong jet of water. Encourage ladybirds and hoverflies. For heavy infestations, use insecticidal soap, spraying in the evening away from bees.
Seedlings chewed overnight
Slugs and snails graze young mizuna, especially in damp weather. Go out after dark and pick them off. Use beer traps or iron phosphate slug pellets, which are safer around pets and wildlife than older types. Follow the label rates.
Plants flower within weeks of sowing
This is bolting, caused by heat, long days or dry soil. It can also follow a cold snap soon after sowing. Sow in early spring or late summer, keep the soil moist, and choose slow-bolting varieties. Pull bolted plants and resow.
Varieties worth growing
- 'Early Mizuna' – Fast-growing green mizuna with finely cut leaves; good for baby leaf and full heads.
- 'Kyona' – The traditional Japanese green mizuna with white stems and serrated leaves; vigorous and cold-tolerant.
- 'Red Kingdom' – Mizuna with deep red-purple leaves and a mild flavour; colourful in salad mixes.
- 'Miz America' – A burgundy-leaved mizuna that suits baby leaf production.