Cool-Season Vegetable

When to Plant Broccoli in Idaho

A nutrition powerhouse that thrives in cool weather. Harvest the main head, then enjoy weeks of side shoots.

The Short Answer

Broccoli are cold-tolerant and do well in Idaho's humid climate. You can direct sow 4 weeks before your last frost — that's as early as May 5 - May 25 in Northern Idaho. Idaho gardeners can also plant a fall crop. Volcanic ash soils in south — excellent for gardening. Rocky soils in mountains. Alkaline in many...

Idaho Frost Dates

Your planting dates depend on which part of Idaho you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Idaho 5a, 5b, 6a May 5 - May 25 Sep 15 - Oct 5
Boise Area 6b, 7a Apr 20 - May 5 Oct 5 - Oct 20
Eastern Idaho 3b, 4a, 4b, 5a May 20 - Jun 10 Sep 1 - Sep 20

Broccoli Planting Schedule for Idaho

Northern Idaho (Zones 5a, 5b, 6a)

Average last frost: May 5 - May 25 · Average first frost: Sep 15 - Oct 5

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Direct Sow
4 wks before frost
Fall Planting
10 wks before first frost

Boise Area (Zones 6b, 7a)

Average last frost: Apr 20 - May 5 · Average first frost: Oct 5 - Oct 20

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Direct Sow
4 wks before frost
Fall Planting
10 wks before first frost

Eastern Idaho (Zones 3b, 4a, 4b, 5a)

Average last frost: May 20 - Jun 10 · Average first frost: Sep 1 - Sep 20

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Direct Sow
4 wks before frost
Fall Planting
10 wks before first frost

Growing Broccoli in Idaho

Broccoli in Idaho's Climate

Broccoli thrives in your cool climate. Spring planting works well — transplant 2-3 weeks before last frost. Unlike warmer regions where heat causes premature bolting, your moderate summer temperatures often allow extended broccoli harvests. Fall broccoli is equally productive. Northern Michigan, Minnesota, and Wisconsin can even grow broccoli through summer in cooler years.

Soil Considerations for Idaho

Volcanic ash soils in south — excellent for gardening. Rocky soils in mountains. Alkaline in many areas.

Idaho Climate & Growing Season

Arid climate. Low humidity. Hot days and cool nights. Irrigation essential. Short season at higher elevations. Broccoli can handle frost well, which is an advantage in Idaho's climate. You can push planting dates earlier in spring and extend into fall.

Growing season length varies across Idaho: Northern Idaho (5a, 5b, 6a) has a last frost around May 5 - May 25, while Eastern Idaho (3b, 4a, 4b, 5a) sees frost end around May 20 - Jun 10. This difference matters for broccoli — but broccoli handle frost well, so the timing difference is less critical.

Growing Tips

Harvest main head while buds are tight. Side shoots will continue producing for weeks after the main harvest.

Companion Planting

Plant broccoli alongside these companions for better growth:

Beets Celery Onions Potatoes

Keep broccoli away from:

Tomatoes Peppers Strawberries

The Bottom Line

Broccoli can be grown successfully across Idaho, but your exact planting dates depend on which region you're in. Northern Idaho gardeners should plan around a May 5 - May 25 last frost, while those in Eastern Idaho can typically plant later. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Broccoli Growing Guide National planting guide with all states Idaho Planting Calendar All plants for Idaho Broccoli in Alabama Alabama planting dates Broccoli in Alaska Alaska planting dates Broccoli in Arizona Arizona planting dates Broccoli in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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