When Is the Best Time to Plant Welsh Onions? A Detailed Guide to the Latest Planting Times

The Welsh onion (Allium fistulosum) is a type of onion. In northern China, Welsh onion production areas mostly raise seedlings and then transplant them, while the main production areas in the middle and lower reaches of the Yellow River mostly sow in autumn, but the seedlings must be strictly controlled to no more than 3 leaves before winter. South of the Yellow River, spring sowing is most common, and sowing should be done promptly once the local soil temperature reaches 7°C. Let us now take a look at the planting times for Welsh onions!

Growing Conditions for Welsh Onions

1. Soil: Welsh onions are suited to loam soil with a pH of 6.5-7.5. The seedling bed should be fertile, loose and well supplied with subsoil moisture. During the emergence stage, prevent the surface soil from crusting. Apply a topdressing once when the seedlings begin to grow rapidly. Control soil moisture 10-15 days before transplanting to prevent excessive vegetative growth and lodging.

2. Fertilizer: Welsh onions are heavy feeders and require balanced applications of nitrogen, phosphorus and potassium. They need more nitrogen in the early growth stage and more phosphorus and potassium later on. Pay special attention to phosphorus application, because a lack of phosphorus leads to poor plant growth and reduced yield. Also pay attention to the sulfur content of the onion field; sulfur deficiency in the soil will affect the yield increase.

3. Temperature: Welsh onions are stress-tolerant, enduring both cold and heat. Although temperature generally has little effect on the growth of Welsh onions, suitable temperature conditions favor high quality and high yield.

4. Water: Welsh onions have few root hairs and a poor ability to absorb water and nutrients. The roots are mostly distributed in the surface layer of the soil and prefer moisture, requiring relatively high soil humidity, but the roots also fear waterlogging; high temperature combined with high humidity can easily cause root death.

5. Light: Welsh onions have moderate light intensity requirements. Because the tubular leaves of Welsh onions can still obtain good light conditions under dense planting, strong light is not needed. Strong light has an adverse effect on the growth of Welsh onions, causing the leaf blades to age, increasing fiber, reducing quality, and even making them unfit for eating.

Planting Times for Welsh Onions

1. Autumn planting time: Sow in early September of the first autumn, overwinter as seedlings, transplant in early to mid-May of the second summer, harvest before winter, and store in cellars or overwinter in the open field. In the third spring they bolt and flower, and seed is harvested in the second season. Seedlings at transplanting time can be sold as small onions (spring onions) from early May to late June; alternatively, around the start of summer (Lixia) they can be planted in flat beds in clumps (clump onions) or grown as trench onions with reduced row and plant spacing to be supplied as autumn onions, or overwintered and supplied as early-spring ram's horn onions.

2. Spring planting time: Sow after the soil thaws in early spring, supply as small onions before the hot summer arrives, or harvest in the same year after transplanting and supply as dry onions or trench onions. They can also be overwintered as ram's horn onions or kept as seed plants for seed production.

3. Summer planting time: Mostly sown from late July to early August, hence also called summer onions (fu cong). By the time winter comes, the plants are relatively large and easily complete the vernalization process, so they sprout early the following spring and quickly bolt and flower. They generally come to market after ram's horn onions.

Planting Methods for Welsh Onions

1. Before transplanting, separate large and small seedlings, and remove diseased, weak, overly small and obviously crooked seedlings. Plant spacing is 35-40 plants per meter, row spacing 1 m, with about 23,000 plants per mu. When transplanting, avoid breaking the onion seedlings; the planting depth should be such that the onion heart is not buried. Too deep and the plants will not grow well; too shallow and the length of the white shank is affected. When transplanting, the leaf surfaces should be arranged perpendicular to the planting trench to facilitate dense planting and management.

2. For the transplanting tool, a garden iron dibber or wooden rod about 1.5 cm in diameter can be used. When transplanting, first make a shallow hole perpendicular to the ground, then insert the seedling, and lift it slightly upward so that the root hairs spread downward and the onion seedling stays straight. If it is left bent, the stem will also be bent at harvest time, making it a substandard product.

3. Transplant on the same side of the onion trench, which helps drainage after rain.

4. After transplanting, press down the loose soil on both sides of the onion plants, then water thoroughly.