Mizuna is a fast-growing Japanese mustard green in the brassica family, grown for its feathery, serrated leaves. It has a mild peppery flavor, milder than arugula or mustard, and is used raw in salads or cooked in stir-fries and soups. It matures quickly and tolerates cooler weather, making it a reliable crop for spring and fall in upstate New York.
Mizuna performs best as a cool-season crop. It bolts in summer heat and long days, so direct sow in early spring and again in late summer for a fall harvest. Cut-and-come-again harvesting works well: trim outer leaves and the plant continues producing. It germinates quickly in cool soil and tolerates light frost, which can improve flavor.
Mizuna is eaten as a leafy vegetable and contains glucosinolates common to brassicas. It has no significant documented medicinal use beyond its nutritional value as a source of vitamins A, C, and K.
Downy mildew
Yellowing on top of leaves with grey-purple fuzz underneath. Spreads rapidly in humid conditions.
Remove affected leaves. Improve air circulation. Avoid overhead watering. Copper spray as preventive.
Flea Beetle
Small round shot-holes scattered across leaves; tiny dark beetles that jump when disturbed. Heavy feeding stunts young plants.
Use floating row covers on seedlings. Remove crop debris and weeds that harbor beetles. Apply kaolin clay or spinosad if damage is severe.
Clubroot
Swollen, distorted roots; wilting in midday heat; stunted growth and yellowing foliage. Plants recover poorly even with watering.
Remove and destroy infected plants with roots. Raise soil pH toward 7.2 with lime. Improve drainage and rotate out of brassicas for several years.
Aphids
Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.
White Rust
Raised white to cream-colored pustules on leaf undersides, with yellow blotches on upper surfaces. Infected tissue may swell or distort.
Remove and destroy infected leaves. Improve air circulation and avoid overhead watering. Rotate brassicas and avoid planting in previously infected soil.