When to plant onion in zone 4a
A planting schedule for onion in USDA hardiness zone 4a, where the typical last spring frost is around May 12, 2026 and the first fall frost around Oct 3, 2026. Dates are computed from NOAA frost normals for a representative location (Stanton, ND) — your exact dates depend on your address.
Onion planting schedule for zone 4a
- Start seeds indoorsFeb 3, 2026 – Sep 1, 2026
- Start hardening offApr 14, 2026 – Oct 20, 2026
- Transplant outdoorsApr 28, 2026 – Oct 27, 2026
Playing it safe with tender crops? Spring frost holds off until about May 26, 2026 in roughly 9 years out of 10.
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Onion in other zones
More crops for zone 4a
Frost dates are NOAA 1991–2020 climate normals for a representative location (Stanton, ND) in zone 4a; your exact dates depend on your address. Schedules are guidance, not guarantees.