Planting Ashitaba
Ashitaba is a cool season herb in the Apiaceae family. Getting the timing right is the difference between a strong stand and a disappointing one, so the windows below are given relative to your own last spring frost and first fall frost rather than a generic calendar date. Look up your local frost dates and count back or forward from there.
Ashitaba is started indoors 8–10 weeks before your last spring frost date, giving seedlings a head start before they move outside.
Transplant young plants outdoors 0–2 weeks after your last frost, once the danger of frost has passed.
Ashitaba can be grown by starting indoors and transplanting. Starting indoors gives the longest, most controlled season, while direct sowing is simplest where the season is long enough.
Spacing and Planting Depth
Give Ashitaba room to mature. The figures below come from verified extension and seed-supplier data for typical varieties.
| Spacing in row | 18 inches |
|---|---|
| Row spacing | 24 inches |
| Plants per sq ft | 0.33 |
| Planting depth | 0.25 inches |
| Sun requirement | Partial sun |
Days to Maturity
Ashitaba reaches maturity in 150–210 days from transplant.
Ashitaba is ready to harvest after about 180 days. Harvest before summer heat or, for fall crops, before a hard freeze, to keep quality high.
Conditions and Care
As a cool-season herb, Ashitaba does its best growing in the cooler weather of spring and fall and tends to bolt or turn bitter in summer heat. It is half-hardy — it withstands light frost but should be protected from a hard freeze.
Ashitaba grows well in partial sun and tolerates some afternoon shade, which can help slow bolting in warm weather. Sow seed about 0.25 inches deep — small seed is sown shallow and barely covered, then keep the soil evenly moist until seedlings establish.
Ashitaba belongs to the Apiaceae family; rotating where you grow members of this family each year helps limit the build-up of soil-borne pests and disease. Ashitaba is generally grown as a single planting each season rather than succession sown.
Growing Notes
Japanese perennial green; slow, erratic germination.