Wyoming planting calendar

When to plant broccoli in Wyoming — sow, transplant & harvest dates

Wyoming is mostly USDA zone 4b (range 3a-6a). Dates below are derived from broccoli's frost tolerance and Wyoming's frost window — not generic national averages.

Broccoli planting timetable for Wyoming

Stage	When in Wyoming	Anchor
Start seeds indoors	mid-April (April 13)	6 weeks before the last frost (late May)
Transplant outside	mid-May (May 11)	14 days before the last frost (late May)
First harvest (estimate)	late July (July 30)	~80 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 Wyoming's climate shifts the broccoli dates

Wyoming's last spring frost averages late May and first fall frost mid-September, which sets the whole planting clock. Wyoming is a high, cold, short-season state. Altitude and wind matter as much as the winter low; frost can come in any summer month at elevation. Sow early — broccoli bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Start seeds indoors 6–8 weeks before last frost; transplant outdoors 2–4 weeks before last spring frost when soil reaches at least 7 °C (45 °F). Mature plants withstand temperatures as low as −6 °C (21 °F). Heads button (form premature small curds) when exposed to temperatures below 10 °C (50 °F) for extended periods as young seedlings, so harden off carefully. In zones 8–10, a second crop is practical as a fall planting, set out in late summer for harvest before hard freezes.

Frost-risk note

Don't plant before late May — a hard freeze can still set young plants back. In the high mountain basins like Jackson Hole (zone 3a) the safe date runs a week or two later.

Regional variation within Wyoming

the high mountain basins like Jackson Hole (zone 3a) runs roughly 1-2 weeks behind the state average; the lower southeast plains near Cheyenne (zone 6a) can plant 1-2 weeks earlier.

Cheyenne — USDA zone 5b
Casper — USDA zone 5a
Jackson — USDA zone 4a
Sheridan — USDA zone 5a

What else to plant in Wyoming 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: 7–29 °C (45–85 °F).
Spacing: 18–24 inches (45–60 cm) between plants.
Days to harvest: ~80 days from planting out.

Frequently asked questions

When is the best time to plant broccoli in Wyoming?

In Wyoming (mostly USDA zone 4b), sow broccoli indoors around mid-April, transplant outdoors mid-May (before the last frost, late May), and harvest from late July. Broccoli 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 Wyoming?

Most of Wyoming sits in USDA hardiness zone 4b, with the state spanning roughly 3a-6a from the high mountain basins like Jackson Hole (zone 3a) to the lower southeast plains near Cheyenne (zone 6a). The last spring frost averages late May and the first fall frost mid-September.

Can you grow broccoli in Wyoming?

Yes. Wyoming's dominant zone 4b supports broccoli — the key is timing. Broccoli 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 Wyoming?

the high mountain basins like Jackson Hole (zone 3a) runs roughly 1-2 weeks behind the state average; the lower southeast plains near Cheyenne (zone 6a) can plant 1-2 weeks earlier.

What else can I plant in Wyoming 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.