Growing scallion (bunching onion) in zone 7b

In zone 7b, the most reliable scallion window opens in late February to mid-March, once soil temperatures reach 40°F consistently. Direct sowing then yields harvest from late April through June, roughly 60 to 80 days after germination depending on variety. Last frost in zone 7b typically falls between late March and early April, but scallion seedlings tolerate light frost without damage, so early starts are low-risk. A second planting in late August or early September takes advantage of cooling fall temperatures and can be harvested from October through December. Fall-planted Evergreen Hardy White frequently overwinters and resumes growth by February. Midsummer planting (June through July) is possible but performance drops under heat and humidity; disease pressure from onion white rot increases substantially in those conditions.

Zone 7b's primary adjustment for scallion growers is managing late-summer disease pressure. Onion white rot thrives in warm, moist soil and can persist in the soil for years once established. Rotating scallions and all alliums on a minimum three-year cycle is more critical here than in drier climates. Raised beds with sharp drainage help reduce infection risk during humid stretches. Japanese beetles and brown marmorated stink bugs will feed on scallion foliage, though neither causes the level of damage they inflict on broader-leafed crops; hand removal is usually sufficient. For fall-overwinter plantings of Evergreen Hardy White, a light mulch layer of 2 to 3 inches of straw provides adequate protection during zone 7b cold snaps without retaining the excess moisture that promotes rot. No supplemental heat protection is needed.