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When to Plant Squash (Winter) in Boise County, ID

Winter squash includes butternut, acorn, delicata, and hubbard varieties grown to full maturity with hard rinds for storage. They develop sweet, dense flesh.

Boise County, Idaho is in USDA Zone 5b. The average last spring frost is May 18 and the first fall frost is September 27, giving you a growing season of approximately 132 days.

At an elevation of 8,023 feet, Boise County receives approximately 24.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Squash (Winter) during the growing season.

Boise County, ID (Zone 5b) Short season
132 days
Last Spring Frost May 18
132 growing days
First Fall Frost September 27

Boise County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 31 Transplant: May 19 🍅 Harvest: Aug 11 – Oct 6
Recommended (50%) ✗ May not fit
Start indoors: Apr 13 Transplant: Jun 1 🍅 Harvest: Aug 24 – Oct 19
Safe Start (90%) ✗ May not fit
Start indoors: May 12 Transplant: Jun 30 🍅 Harvest: Sep 22 – Nov 17

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 320 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Squash (Winter) needs ~1,450 GDD — county provides 1,914 GDD Excellent fit

Squash (Winter) Planting Timeline โ€” Boise County, ID

Squash (Winter) Planting Calendar

Activity When Date Range
Start Indoors April 13 Apr 13 โ€“ Apr 27
Transplant Outdoors June 1 Jun 1 โ€“ Jun 15
Direct Sow May 25 May 25 โ€“ Jun 15
Harvest August 24 Aug 24 โ€“ Oct 19

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

132 days

Growing Tips for Boise County

Direct sow after last frost on rich mounds. Allow ample space for sprawling vines. Cure harvested fruits in the sun for 10 days before storing in a cool, dry place.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Squash (Winter) in Boise County, ID?

Boise County is in Zone 5b with an average last frost of May 18. Plan your Squash (Winter) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Boise County, ID?

Boise County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 18 and first fall frost is September 27.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Boise County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Boise County, ID. Local conditions may vary. Last updated: April 2026.