PROBLEM TO BE SOLVED: To provide an extremely effective cultivation method of welsh onion capable of harvesting not only in spring that is the ordinary harvest season but also in off-season such as autumn and winter. SOLUTION: In the planting of welsh onion, this method plants the bulbs of the welsh onion in an interval that estimates the size of the offshoot and sufficiently grown-up welsh onion in the next spring and disuses any thin out, and plants bulbs of welsh onion between the planted bulbs of welsh onion in an interval estimating the thin out, properly thins out the grown welsh onion, finally harvests the welsh onion estimated to harvest in the next spring.
