Gadenin日本語Get the appSow into cooling soil, not warming soil
Mibuna germinates from about 40F to 85F (4C to 29C), which means it will sprout for you almost any time the ground is not frozen. That reliability is a trap. Seed that comes up happily in early summer heat is seed that will throw a flower stem before the plant is the size of your hand, because the plant is reading day length rather than temperature. Germination tells you nothing about whether the sowing was well timed.
The sowing that pays is the one made after midsummer heat has broken, through early and mid autumn. Plants sown then bulk up as the nights cool, the strap leaves stay thick and glossy, and there is no flowering pressure at all until the following spring. In most gardens that single window will feed you from autumn into late winter off repeated cuts. A second, smaller window opens in late winter as soon as the ground is workable, but treat that crop as a short one: it will run to seed as the days lengthen.
Sow shallow. A quarter inch (5 mm) is right; a half inch (12 mm) is the deepest that still comes up evenly. The seed is small and the seedling has almost no reserve to punch through a crust, so if your soil caps after rain, cover the drill with sieved compost or old potting mix rather than the clay you just dug out of it.
| Soil temperature | Days to emerge | What to expect |
|---|---|---|
| 45F (7C) | 8 to 12 | Slow but even; fine for a late sowing |
| 55F (13C) | 5 to 7 | Ideal; strong, stocky seedlings |
| 65F (18C) | 3 to 4 | Fast, but watch for stretching in low light |
| Above 80F (27C) | 3 | Comes up, then bolts young. Not worth sowing |
Space it wider than you think, because the leaves lie down
This is where mibuna differs most from its serrated sister. Mizuna makes a fine, feathery clump that stands upright and packs tightly. Mibuna makes long, smooth, strap-shaped leaves on a flat rosette that spreads sideways and leans out over its neighbors. A mature plant grown for full-size leaves will occupy a circle twelve to fourteen inches (30 to 35 cm) across, and it does that at the expense of anything sown next to it.
So choose your spacing by how you intend to pick, and commit to it. If you want a dense baby-leaf bed to shear over with scissors, sow a broad band and never thin past two inches (5 cm). If you want full plants that you strip leaf by leaf for months, get them out to eight or ten inches (20 to 25 cm) and give the rows a foot (30 cm) between them so air moves through the crowns.
| Growing for | Plant spacing | Row spacing | First pick |
|---|---|---|---|
| Baby leaf, sheared | 1.5 to 2 in (4 to 5 cm) | 6 in (15 cm) | 21 to 28 days |
| Medium leaf, picked singly | 5 to 6 in (13 to 15 cm) | 10 in (25 cm) | 35 to 45 days |
| Full rosettes, long season | 8 to 10 in (20 to 25 cm) | 12 in (30 cm) | 50 to 60 days |
Thin twice, and thin harder than feels right
Almost every disappointing mibuna crop is an unthinned one. Crowded plants make thin, pale straps instead of thick ones, hold moisture around the crown where rot starts, and bolt earlier because a stressed plant reproduces sooner. Thinning in two passes is easier on your nerve than one brutal pass, and the first thinnings are worth eating.
- First pass at the second true leaf When seedlings show two true leaves beyond the seed leaves, pull to roughly half your final spacing. Pinch them off at soil level rather than tugging, so you do not lift the roots of the plant you are keeping. These thinnings are the mildest mibuna you will ever taste and belong in a salad that day.
- Second pass when leaves touch Two to three weeks later the remaining plants will be touching again. Take them out to final spacing now, choosing the keepers by crown shape rather than size: a flat, symmetrical rosette outperforms a tall leggy one over a long season. Water the row afterwards to resettle the soil around the plants that stayed.
- Fill the gaps rather than resowing the bed If slugs took a few seedlings, drop two or three seeds into each gap rather than starting again. They will catch up within a couple of weeks at cool-season growth rates and stagger your picking usefully.
Record the sowing date and the date of first emergence for each batch. After one season those two numbers, next to what the weather did, tell you your own sowing window far more accurately than any packet.
Sow again before you need to
Mibuna regrows willingly after cutting, but each regrowth is a little coarser and a little more pungent than the one before, and after four or five cuts the crowns get woody. The fix is succession, not persistence. Put in a fresh short row every two to three weeks through the autumn window, and stop sowing about eight weeks before your ground normally freezes hard so that the last batch has size on it before growth stalls.
Under a cold frame or a low tunnel you can push the last sowing later, but do not expect it to grow much in the depths of winter. Winter cover is there to hold a crop you already grew, not to grow one from scratch. A plant that goes into hard cold at three inches (8 cm) tall will sit there until the light returns; one that goes in at eight inches (20 cm) will feed you the whole time.