Gadenin日本語Get the appUse fresh seed and sow it on the surface
Mitsuba seed loses viability faster than almost anything else in the umbellifer family. Seed from the current season germinates well, seed a year old germinates thinly, and seed two years old is mostly dead however carefully it was stored. If you have a packet of unknown age, sow it three times as thickly as you think you need and treat the result as a bonus.
The seed also needs light to germinate. Bury it half an inch and most of it will simply sit in the dark and rot. Scatter it on a firmed, damp surface, press it down with the flat of your hand or the back of a board so each seed is in contact with soil, then sift no more than an eighth of an inch (3 mm) of fine compost over the top. Some gardeners sow bare and cover the bed with damp burlap instead, lifting it the day the first seedlings show.
Germination takes fourteen to thirty days, and it is uneven within that window. The first seedlings appearing at two weeks and the last at four weeks from the same sowing is normal, not a sign of bad seed. Mark the sowing date and leave the patch alone for a full month before you decide it has failed.
Mitsuba seed germinates best between 55 and 68F (13 to 20C). Above 77F (25C) germination drops away sharply, which is why summer sowings in warm soil usually disappoint and autumn or early spring sowings do not.
When to sow, and why autumn beats summer
There are two good windows. The first is early spring, as soon as the soil is workable and running around 50 to 60F (10 to 16C) — the seedlings come up as the tree canopy is closing over them, which is exactly the light they want. The second, and the better of the two in most gardens, is autumn: sow six to eight weeks before your first hard frost, let the seedlings make three or four leaves, and they will sit through the winter and grow away early the following spring, weeks ahead of any spring sowing.
Autumn sowing also matches the way mitsuba behaves in the wild, where seed drops in late summer, chills over winter and comes up in the cool damp of spring. Seed that has been through a cold spell germinates faster and more evenly. If you are sowing in spring from a packet, four weeks in a damp bag of sand in the refrigerator before sowing has the same effect.
| Item | Figure | Why it matters |
|---|---|---|
| Sowing depth | Surface, or 1/8 inch (3 mm) of sifted cover | The seed needs light; deep sowing is the commonest cause of a failed row |
| Soil temperature | 55 to 68F (13 to 20C) | Above 77F (25C) germination becomes erratic and thin |
| Days to emerge | 14 to 30 | Uneven emergence across that window is normal; do not re-sow early |
| Seed age | Current season only | Viability falls steeply after one year in storage |
| First thinning | At two true leaves, to 2 inches (5 cm) | Crowded seedlings draw each other up thin and damp off |
| Final spacing | 6 to 8 inches (15 to 20 cm) | Each crown wants room to send up its own flush of stems |
Sow it where it will stay
Mitsuba makes a thin taproot early, and like most umbellifers it resents having that root turned sideways at the bottom of a shallow tray. A plant that has been checked in a module never bulks up in the way a direct-sown one does, and it is more likely to run to flower in its first summer instead of building a crown.
So choose the permanent spot first — dappled shade under a deciduous tree, the north side of a fence, the shaded strip behind taller crops — and sow into it. If you must raise plants under cover, use deep cells or root trainers at least three inches (7.5 cm) deep, sow two or three seeds per cell, thin to the strongest, and plant out before the root reaches the base. Plants going out at four true leaves establish far better than ones held back until they look sturdy.
- Clear and firm the surface Rake out stones and lumps and firm the top inch (2.5 cm). Mitsuba seed is small and will vanish into a rough, fluffy seedbed where it never makes soil contact.
- Water before sowing, not after Water the strip and let it drain. Sowing onto damp soil means the seed takes up water immediately, and it avoids the heavy watering that washes surface-sown seed into clumps.
- Scatter and press, do not bury Broadcast thinly along a band six inches (15 cm) wide, then press the seed in with a board. Sift the barest dusting of compost over it if the site is windy.
- Keep the surface damp for a month A fine rose every day or two in dry weather is enough to wet the top half inch (12 mm). Seed that swells and then dries out for a day is dead seed.
- Thin in two passes Pinch seedlings off at soil level at two true leaves, then again a fortnight later to the final spacing. Pulling them lifts their neighbors, because the roots tangle early.
Sowing once, then never again
The point of getting a mitsuba sowing right is that it is usually the only one you will make. Plants that reach their second year flower, set seed and drop it, and the seedlings that follow are stronger than anything you will raise from a packet because the seed has never been dried and stored. Within two or three seasons a shaded corner will look after itself.
That means the first sowing is worth some care over placement. Put it where you are happy for a low, self-renewing patch to sit for years, not in a bed you rotate. Record the sowing date, the spot, the seed's age and the date the first seedling appeared. Next time you will know exactly how long your soil takes to bring mitsuba up, and whether an autumn or a spring sowing works better in your garden.