How do you grow mizuna microgreens? Sow about 9.5 grams of mizuna seed per 10×20 tray, press it into moist mix, and keep it covered and near 75°F (24°C) until it sprouts. Then move the tray under light, bottom water, and cut at 1/2–2 inches (1–5 cm). Johnny’s Selected Seeds reports an average of 12 days to first true leaf.
Key takeaway: Mizuna microgreens are one of the fastest, mildest brassica micros you can grow. Penn State Extension describes mizuna (Brassica rapa var. nipposinica, also listed as var. japonica) as an Asian green with a mild, mustard-like peppery flavor that can also be grown as microgreens, and Johnny’s Selected Seeds places it in its fast-growing 10–15 day group.
| Factor | Guideline | Source |
|---|---|---|
| Seeding rate for mizuna microgreens | 9.5 g per tray (about 3 flats per oz) | Johnny’s Selected Seeds |
| Days to harvest | About 12 days to first true leaf | Johnny’s Selected Seeds |
| Germination temperature | 75°F (24°C), then 60°F (16°C) root zone | Johnny’s Selected Seeds |
| Air temperature | 65–75°F (18–24°C) | Johnny’s Selected Seeds |
| Harvest height | 1/2–2 in (1–5 cm) | Johnny’s Selected Seeds |
| Flavor | Mild, mustard-like and peppery | Penn State Extension |
What Do Mizuna Microgreens Taste Like?
Mild and gently peppery. Penn State Extension says mizuna has a mild mustard-like peppery flavor, and Johnny’s describes it as a fast-growing, unique, mild-flavored mustard green with fancy, toothed leaves. Johnny’s says the angular true leaves and bright green color make mizuna an excellent addition to any mix, so it pairs well with spicier radish or mustard.
Penn State Extension adds that mizuna is also called Japanese mustard greens, spider mustard or water greens.
- Look: fancy, toothed, bright green leaves.
- Taste: milder than most mustard micros.
- Use: salads, sandwiches, soups and garnishes.
How Much Seed Do Mizuna Microgreens Need?
About 9.5 grams per standard tray. Based on its yield trial, Johnny’s recommends seeding 9.5 g of mizuna per tray, or roughly 3 flats per ounce of seed, and lists about 271,200 seeds per pound. Penn State Extension says small-seeded brassicas should be sown densely, up to about 12 seeds per square inch (6 per cm²).
Our microgreen seed density guide shows how to scale that to any tray size.
How Do You Grow Mizuna Microgreens Step by Step?
Follow Johnny’s brassica routine. Broadcast seed thickly on moist potting mix or a soilless medium in a shallow tray, with seeds 1/8–1/4 inch (3–6 mm) apart. Press them firmly into the surface and cover lightly with mix, vermiculite or a humidity dome. Johnny’s microgreens chart notes that all of its microgreens are suitable for hydroponic growing.
- Fill a shallow tray with moist mix or a grow mat.
- Weigh about 9.5 g of untreated mizuna seed.
- Broadcast evenly and press seeds into the surface.
- Cover lightly or stack a blackout lid on top.
- Keep the root zone near 75°F (24°C) until germination.
- Uncover after sprouting and move under light.
- Bottom water to keep the medium evenly moist.
What Temperature and Light Do Mizuna Microgreens Need?
Warm to start, cooler to grow. Johnny’s says ideal soil temperature is 75°F (24°C) until germination, then 60°F (16°C), with air at 65–75°F (18–24°C); above 75°F (24°C) raises disease pressure. Oregon State University Extension suggests covering trays for about three to four days until seeds sprout, then using a lamp about 3 inches (7.5 cm) above the plants for around 15 hours a day.
- Blackout: about 3–4 days, or until most seeds sprout.
- Light: about 15 hours a day under a lamp.
- Airflow: a small fan reduces damping-off.
How Do You Water Mizuna Microgreens?
From below. Johnny’s recommends bottom watering or misting so mix does not splash onto seedlings, and says to keep moisture even without letting the medium dry out. In potting mix, plain water is usually enough; on nutrient-free mats, a dilute fertilizer solution can help. Our microgreens bottom watering guide walks through the method.
When Do You Harvest Mizuna Microgreens?
In about 12 days. Johnny’s trial averaged 12 days to maturity when mizuna was harvested at the first true leaf rather than the cotyledon stage. It recommends harvesting at 1/2–2 inches (1–5 cm) tall with scissors or a sharp knife, handling the greens as little as possible. Penn State Extension says microgreens in general are harvested 7 to 21 days after germination.
See how to harvest microgreens for cutting and drying tips.
How Long Do Mizuna Microgreens Last?
Up to about a week or more if stored well. Johnny’s says microgreen shelf life ranges from 5 to 10 days under proper storage conditions, and that microgreens must be washed before serving. Oregon State University Extension suggests wrapping harvested greens in a paper towel inside a plastic bag in the refrigerator and using them within one to two days for best quality.
Why Are My Mizuna Microgreens Moldy or Falling Over?
Usually too wet, too warm or too crowded. Johnny’s says dense microgreen plantings are prone to damping-off with poor air circulation and saturated media, and recommends horizontal airflow fans, clean media and water, and appropriate seeding density. Oregon State University Extension adds that seeds and seedlings can rot or mold if the medium is too wet and cold.
Are Mizuna Microgreens Healthy?
They are a nutrient-dense brassica. Penn State Extension says mizuna is an excellent source of vitamins A, C and K-1, and a USDA Agricultural Research Service study of 25 microgreens found they contained, on average, about five times more vitamins and carotenoids than mature leaves. Values vary widely by species, so treat mizuna microgreens as one healthy part of a varied diet.
FAQ About Mizuna Microgreens
How long do mizuna microgreens take to grow?
About 12 days to first true leaf, per Johnny’s trial.
How much seed per tray?
About 9.5 g per standard tray.
Do mizuna microgreens need a blackout period?
A few days of cover until sprouting helps.
Can you grow mizuna microgreens hydroponically?
Yes, on grow mats with bottom watering.
What do mizuna microgreens taste like?
Mild, mustard-like and slightly peppery.
How tall should they be at harvest?
About 1/2–2 inches (1–5 cm).
Sources
- Johnny’s Selected Seeds — Mizuna Microgreen Seed
- Penn State Extension — Mizuna: an Asian Green
- Penn State Extension — The ABCs of Microgreens
- Oregon State University Extension — Microgreens
- USDA Agricultural Research Service — Specialty Greens Pack a Nutritional Punch
- Johnny’s Selected Seeds — Microgreens Comparison Chart
- Photo credits (Wikimedia Commons, edited with titles): Mizuna microgreen by Idéalités (CC BY-SA 4.0); Mizuna seedlings by Nadiatalent (CC BY-SA 4.0); Mizuna 001 by Flickr user masahiko(Masahiko Satoh) (CC BY 2.0)