Gadenin日本語Get the appSow into cool soil, not warm soil
Mizuna germinates over a very wide range, roughly 40F to 85F (4C to 29C), and comes up in three to five days when the soil is around 60F (15C). That range is so forgiving that most growers sow at the wrong time by accident: they sow in the heat of early summer because the seed sprouts, then wonder why the plants run to seed at four inches tall.
The two windows worth using are late summer into autumn, and again from late winter as soon as the soil is workable. Autumn sowings are the better crop by a wide margin. The plants size up as the nights cool, the leaves stay tender, and there is no pressure to bolt. A crop sown after midsummer heat has passed will still be cutting long after the first hard frosts have taken the basil and the beans.
Sow shallow. A quarter of an inch (5 mm) is right, and a half inch (12 mm) is the deepest you should go. The seed is small and the seedling has very little reserve to push through a crust. If your soil caps after rain, cover the row with sieved compost or old potting mix rather than the soil you dug out.
| Soil temperature | Days to emerge | What to expect |
|---|---|---|
| 40F (4C) | 10 to 14 | Slow but reliable; fine for the last autumn sowing |
| 50F (10C) | 6 to 8 | Even stands, strong seedlings |
| 60F (15C) | 3 to 5 | The sweet spot |
| 75F (24C) | 3 | Fast, but leggy and prone to bolting later |
| Above 85F (29C) | Erratic | Patchy germination; wait for it to cool |
Spacing depends on how you intend to pick
This is the one decision that changes everything downstream, and it is worth making before the seed goes in the ground. Mizuna is grown two completely different ways from the same packet. Sown thick and cut young, it is a baby leaf crop harvested with scissors an inch above the crown. Sown wide and left alone, a single plant builds a fountain of a hundred or more slender stems, easily fifteen inches (38 cm) across, and you pick individual stems from the outside for months.
Decide first, then sow to match. The commonest disappointment with mizuna is a bed sown at baby leaf density but left to grow to full size: the plants crowd, the inner leaves yellow, and the whole patch goes down to rot at the first wet spell.
For baby leaf, scatter or drill the seed so plants stand about one inch (2.5 cm) apart in rows four to six inches (10 to 15 cm) apart. For full heads, aim for eight to twelve inches (20 to 30 cm) each way. If you want both, sow a wide-spaced row and a thick band, and treat them as separate crops.
| Growing style | Final spacing | First cut | How you pick |
|---|---|---|---|
| Baby leaf | 1 in (2.5 cm) | 21 to 30 days | Shear the whole band an inch above the crown |
| Medium | 4 to 6 in (10 to 15 cm) | 35 to 45 days | Take outer stems, leave the center |
| Full head | 8 to 12 in (20 to 30 cm) | 50 to 60 days | Outer stems for months, or lift the whole plant |
Thin twice, and thin harder than feels right
Mizuna seed germinates so reliably that almost everyone sows too thickly and then cannot bring themselves to pull the surplus. Unthinned plants stretch, the stems go thin and floppy, and airflow at the crown drops to nothing. Do it in two passes so you are never left with a gap if something gets eaten.
- First thinning, at the first true leaf About a week to ten days after emergence, when the first feathery true leaf shows past the round seed leaves. Take out anything crowded, weak or pale and leave plants roughly one inch (2.5 cm) apart. Snip at soil level with scissors rather than pulling, so you do not lift the neighbor's roots.
- Second thinning, at three or four true leaves Two to three weeks after the first. Open the stand out to its final spacing for the style you chose. These thinnings are a real salad, not waste: at this size the leaves are mild, and the whole seedling including the stem is worth eating.
- Firm and water after each pass Thinning loosens the soil around the plants you kept. Press the soil back with your fingers and water gently, or the survivors sit in an air pocket and check for several days.
If the seedlings are stretching towards the light and toppling within a week of emergence, they are short of light, not water. Move a container crop somewhere brighter immediately; a bed crop in that state usually recovers once thinned.
Sow again before you need to
One sowing does not give a season of mizuna even with cut-and-come-again picking, because each stand eventually tires or bolts. Sow a short row every two to three weeks through the cool part of the year. A row three feet (90 cm) long is enough for most households at each sowing, and successive rows overlap so you never have a gap.
Write down the sowing date for every row and the spacing you used. When one row is markedly better than the one beside it, the reason is almost always in those two numbers. After two seasons of notes you will know your own soil temperature window better than any packet can tell you, and you will have a record of the date the spring sowings started to bolt, which is the number that sets your last useful spring sowing next year.