Nebraska planting calendar

When to plant onions in Nebraska — sow, transplant & harvest dates

Nebraska is mostly USDA zone 5b (range 4b-6a). Dates below are derived from onions's frost tolerance and Nebraska's frost window — not generic national averages.

Onions planting timetable for Nebraska

Stage	When in Nebraska	Anchor
Start seeds indoors	mid-February (February 14)	10 weeks before the last frost (late April)
Transplant outside	late March (March 28)	28 days before the last frost (late April)
First harvest (estimate)	mid-July (July 16)	~110 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Nebraska's climate shifts the onions dates

Nebraska's last spring frost averages late April and first fall frost early October, which sets the whole planting clock. Nebraska has a continental plains climate — cold winters, hot windy summers, and a season that shortens going north and west. Sow early — onions bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Onions are day-length sensitive: long-day varieties (zones 1–6) begin bulbing when days exceed 14 hours, short-day types (zones 7–10) bulb at 10–12 hours, and intermediate-day varieties span zones 5–6. Start seeds indoors 10–12 weeks before the last spring frost and transplant out 4–6 weeks before it — young onion seedlings tolerate frost down to about -6 °C once hardened off. In zones 8–10 a second planting from sets in autumn is common, overwintering for an early-summer harvest.

Frost-risk note

Don't plant before late April — a hard freeze can still set young plants back. In the northern Sandhills and Panhandle (zone 4b) the safe date runs a week or two later.

Regional variation within Nebraska

the northern Sandhills and Panhandle (zone 4b) runs roughly 1-2 weeks behind the state average; the southeast near the Missouri River (zone 6a) can plant 1-2 weeks earlier.

Omaha — USDA zone 5b
Lincoln — USDA zone 5b
Grand Island — USDA zone 5a
Scottsbluff — USDA zone 5a

What else to plant in Nebraska around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 10-35 °C (50-95 °F).
Spacing: 4-6 inches (10-15 cm) between plants.
Days to harvest: ~110 days from planting out.

Frequently asked questions

When is the best time to plant onions in Nebraska?

In Nebraska (mostly USDA zone 5b), sow onions indoors around mid-February, transplant outdoors late March (before the last frost, late April), and harvest from mid-July. Onions are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

What USDA zone is Nebraska?

Most of Nebraska sits in USDA hardiness zone 5b, with the state spanning roughly 4b-6a from the northern Sandhills and Panhandle (zone 4b) to the southeast near the Missouri River (zone 6a). The last spring frost averages late April and the first fall frost early October.

Can you grow onions in Nebraska?

Yes. Nebraska's dominant zone 5b supports onions — the key is timing. Onions are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

Does the planting date change across Nebraska?

the northern Sandhills and Panhandle (zone 4b) runs roughly 1-2 weeks behind the state average; the southeast near the Missouri River (zone 6a) can plant 1-2 weeks earlier.

What else can I plant in Nebraska around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.