Sow at a depth of approx.
0.23 inches (0.6 cm) and aim for a distance of at least
0.39 inches (1.0 cm) between Bunching onion plants. Soil temperature should be kept higher than
15°C / 59°F to ensure good germination.
By our calculations, you should look at sowing Welsh White about 28 days before your last frost date.
As Welsh White is very hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.