Tatsoi is a cool-season Asian green in the Brassica family, grown for its small, spoon-shaped dark green leaves that form low rosettes. It is fast-growing and cold-tolerant, making it a reliable crop for spring and fall in Zone 6b. Leaves are eaten raw in salads or cooked in stir-fries and soups.
Direct sow in cool soil; tatsoi bolts in summer heat and long days, so timing favors early spring and late summer plantings. Harvest individual outer leaves or cut the whole rosette. It germinates quickly and can be grown as a cut-and-come-again crop or harvested young as baby greens. It tolerates light frost and can survive into early winter under row cover.
Tatsoi is used as a culinary leafy green, similar to bok choy and spinach. It is a source of vitamin C, vitamin K, and carotenoids.
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.