Mizuna

Mizuna (Brassica rapa var. nipposinica) is ready to cut at 20 days from sowing if you harvest baby leaves. That speed, combined with mild flavor and genuine bolt resistance compared to arugula and spinach, makes it one of the most practical additions to a continuous-harvest salad garden. It’s a Japanese mustard green with feathery, deeply cut leaves and a flavor that runs from mild and slightly peppery at baby-leaf stage to more assertive at full size.

It’s in the same species as bok choy and turnip (Brassica rapa) but a distinct variety bred for leaf production. You’ll find it in specialty grocery stores as part of mesclun mix or sold as loose leaves at farmers markets. The per-pound price reflects its specialty positioning: $3.00-$5.00/lb at markets where it appears (USDA AMS Specialty Crop Market News, 2023).

What you’re actually growing

Mizuna leaves are deeply serrated, bright green, and form loose rosettes rather than the tight heads of lettuce or cabbage. The flavor is mild mustard at baby stage - less sharp than arugula, more complex than butterhead lettuce. At full size (35-40 days), the flavor increases and the texture becomes sturdier, more appropriate for stir-frying than raw eating.

Green mizuna is the standard. ‘Red Mizuna’ is a purple-veined selection with more pronounced color that holds in salad mixes; the flavor is similar to the green type. Both are bolt-resistant compared to arugula, meaning you’ll get more cutting time before the plant switches to seed production in warm weather.

Mizuna is sometimes grouped with mustard greens culturally but it’s a milder, faster plant with a distinct feathery leaf structure. If you’ve been eating arugula and want something in a similar position but more flexible, start there.

The ROI case

A $2.49 packet plants a generous bed. At baby-leaf density (broadcast seeding or 2-inch spacing), a single 4x4-foot bed produces multiple cuts. The cut-and-come-again characteristic means you’re getting 2-4 harvests from one sowing before bolting. At $3.00-$5.00/lb and multiple cuts, the return per square foot from a baby-leaf mizuna bed compares favorably to most other greens.

The velocity argument matters here too: 20 days to first cut means mizuna fits into shoulder-season gaps when other crops aren’t producing. Sow in early spring before tomato transplant time and get 3 weeks of fresh salad greens before the season is officially in gear.

Growing requirements

Direct sow spring and fall; mizuna handles light frost (down to about 25°F) and is significantly more cold-tolerant than arugula or spinach. For spring, sow 4-6 weeks before last frost - mizuna can handle temperatures that would kill tender seedlings of warm-season crops. For fall, sow 6-8 weeks before first frost for a harvest that extends into cool fall and early winter.

Broadcast seed lightly over prepared soil (1/8 inch deep), rake in gently, and water. For cut-and-come-again beds, density works in your favor - the seedlings shade out weeds quickly. For full-size plants, thin to 4-6 inches.

Soil pH 6.0-7.5. Mizuna is adaptable. Two inches of compost worked in before sowing is all the fertility it needs.

Partial shade slows bolting in spring and extends the productive window in warmer climates. If you have a spot that gets 4-5 hours of morning sun and afternoon shade, that’s a useful location for mizuna in late spring.

Water 1 inch per week. Consistent moisture produces faster growth and better texture. Dry stress speeds bolting.

What goes wrong

Flea beetles (Phyllotreta species) put small round holes in young leaves - the same problem they cause in arugula, mustard, and other brassicas. Row covers prevent it. If flea beetles are severe in your garden, cover mizuna from germination.

Aphids on new growth. Water blast for light infestations; insecticidal soap for heavier colonies.

Downy mildew (Peronospora brassicae) in wet spring conditions causes yellow patches with gray fuzz on undersides of leaves. Space plantings for air circulation, avoid overhead watering. Not usually severe enough to require treatment unless persistent.

Bolting is triggered by long days and heat. When the central stem begins to elongate and the leaves become smaller and more pointed, the plant is transitioning to flower. At baby-leaf stage, you have considerable time before this happens. At full-leaf harvest, the window is shorter. Fall plantings run counter to the day-length trigger and extend the harvest significantly.

Harvest and storage

For baby leaves: cut 1-2 inches above soil at 20-25 days. The stub regrows; expect 2-3 more cuts. For full-size plants: cut individual outer leaves at 35-40 days, or cut the entire plant 2 inches above soil for a single large harvest.

Fresh mizuna is fragile. Use within 3-5 days; store in a damp paper towel in a sealed bag in the refrigerator. For longer storage, blanch briefly and freeze as you would spinach or other greens.

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Related crops: Arugula, Tatsoi

Related reading: Succession Planting Calendar - timing fast-maturing greens in spring and fall to keep cutting throughout both seasons