Mizuna Plant Profile

mizuna japanese green leaf
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Mizuna is a mild-flavored Japanese mustard that is commonly grown for commercial salad mixes. It has lobed green leaves and a pleasant bitter taste. Mizuna is a close relative to the turnip but has a flavor all its own. Ridiculously easy to grow, it re-grows well when harvested as a cut-and-come-again green. The fringed, serrated leaves add decoration and spice to salads and are crisp enough to hold up to light blanching or sautéing. The purple-leaved varieties are especially pretty when used in cooking. Traditional Japanese chefs tend to pickle the leaves and use them as a condiment.

In certain climates, mizuna is a biennial, although plants may go to seed after their first year, if left in the ground. You can overwinter this green in a cold frame, hoop house, or greenhouse, but plan on eating it before it starts to flower. Most gardeners prefer to plant mizuna by seed as an annual, alongside other salad greens. Baby greens can be harvested in about 20 days; full heads should form around day 40. In climates with hot summers, mizuna is best planted in spring and late summer because it prefers cool weather. In places with warm winters, it can also be planted in fall and should survive the winter without protection.

Botanical Name Brassica rapa var. japonica (synonym: Brassica rapa nipposinica)
Common Name Mizuna kyona, shui cai
Plant Type Biennial green
Mature Size 5 to 7 inches high, 10 to 15 inches wide
Sun Exposure Full sun, partial shade
Soil Type Well-drained, rich soil
Soil pH Neutral (6.5 to 7.0)
Bloom Time Spring (not typically grown for flowers)
Flower Color Yellow
Hardiness Zones 4 to 9
Native Area Kansai region of Japan

How to Plant Mizuna

Sow seeds directly in your outdoor garden about two weeks before your last frost date. Plant seeds 1/4 inch deep in your garden bed, spaced at 1 inch apart. You can also broadcast the seed (dispersing it over a large section of your garden). Broadcasting may result in seed waste, however, as some seeds may not be sown deep enough to germinate. Thin and eat baby greens when they are a couple of inches tall. If you are growing full-sized heads of mizuna, thin plants to at least a 6-inch spacing.

If desired, you can start seeds indoors four to five weeks before your last frost date. Seeds are quick to germinate, usually within four to eight days. Transplant indoor-grown seedlings when they are at least four weeks old. Be very careful not to disturb the roots of seedlings when transplanting; these Asian greens are vulnerable to root damage.

Mizuna is a fast maturing plant, making it relatively low-maintenance. All you need to do is make sure it stays watered. Succession planting every two weeks will ensure a longer harvest period. Then, take a break during the heat of the season and resume planting late in the summer, continuing through fall. Seeds can be harvested and saved for up to four years.

Mizuna Care

Light

Mizuna grows best in sunny spots that receive three to four hours of direct sunlight a day. However, this plant thrives in cool weather, making spring and fall crops abundant. It is slow to bolt, but hot temperatures and long sunny days may accelerate the bolting process.

Soil

Mizuna likes well-drained soil amended with rich organic matter. Since Mizuna is a leafy crop, it also thrives in soil with plenty of nitrogen. This green will grow in a soil pH from 6.0 to 7.5, but something in the 6.5 to 7.0 range is best.

Water

Keep your garden soil evenly moist for best growing results. If the soil is too wet, mizuna roots may rot. If it is too dry, the plants may fail to thrive.

Temperature and Humidity

Like most greens, mizuna favors the cool weather of spring and fall. Hot temperatures will eventually cause the green to bolt.

Fertilizer

Chemical fertilizers should never be used on greens meant for consumption. Mizuna should get enough nutrients from soil heavily composted with organic materials. If an extra boost is needed, try spraying a dilute fish emulsion solution on the plants midseason, and be sure to wash the leaves thoroughly before eating them.

Mizuna Varieties

Most seed packets are simply labeled "mizuna," however, sourcing specialty seeds will allow you to grow varieties with the traits you like and will help guarantee the success of next year's crop. Here are some gardener favorites:

  • Komatsuma: This plant has slender leaves and is very drought- and frost-tolerant.
  • Kyona: A green with frilly leaves on pencil-thin stalks; it's great when eaten fresh.
  • Kyoto: Featuring deeply serrated leaves, this variety has a pleasant bite.
  • Red Komatsuna: This variety is not as robust as the other green types, but it's very flavorful.
  • Vitamin Green: This vitamin-rich green has smooth, dark green leaves and is slow to bolt.

Common Pests

Mizuna is not prone to the usual brassica diseases, but, unfortunately, it is attractive to some pests. Flea beetles do the most damage to this leafy green, and row covers help to minimize its exposure to the pests. Slugs, whiteflies, and aphids can also harm the leaves if not kept in check.