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When to Plant Squash (Winter) in Twin Falls County, ID

Twin Falls County, Idaho Zone 6b May

Your May gardening checklist

Each item below is timed to Twin Falls County, Idaho's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 10
Avg. first frost October 4
Soil temp (4") 49°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
  1. Move squash (winter) from tray to bed

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Scatter squash (winter) into prepared beds

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

June prep starts now
  • Starting indoors: squash (winter)

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

Twin Falls County, Idaho is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.

At an elevation of 4,584 feet, Twin Falls County receives approximately 21.8 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Squash (Winter) during the growing season.

Twin Falls County, ID (Zone 6b) Short season
147 days
Last Spring Frost May 10
147 growing days
First Fall Frost October 4

Twin Falls County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 27 Transplant: May 15 🍅 Harvest: Aug 7 – Oct 2
Recommended (50%) ✗ May not fit
Start indoors: Apr 5 Transplant: May 24 🍅 Harvest: Aug 16 – Oct 11
Safe Start (90%) ✗ May not fit
Start indoors: Apr 30 Transplant: Jun 18 🍅 Harvest: Sep 10 – Nov 5

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.

Soil Compatibility in Twin Falls County

How your county's soil matches Squash (Winter)'s growing requirements.

Soil pH

Your soil pH (6.5–8.0) is more alkaline than Squash (Winter) prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Twin Falls County is excellent for Squash (Winter) — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Squash (Winter).

How to Plant Squash (Winter)

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Squash (Winter)

2
successive plantings in your 147-day season

Sow every 9.1 weeks. Last sowing by Jun 06 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 592 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Squash (Winter)

Squash (Winter) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Squash (Winter) Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 4.3" 2.3" 2" 💧 Light watering
Jun 4.3" 1.6" 2.7" 🚿 Regular watering
Jul 4.3" 1.9" 2.4" 🚿 Regular watering
Aug 4.3" 2.4" 1.9" 💧 Light watering
Sep 4.3" 1.9" 2.4" 🚿 Regular watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 1.3" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Twin Falls County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Squash (Winter) Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Squash (Winter) needs ~1,450 GDD — county provides 2,131 GDD Excellent fit

Squash (Winter) Planting Timeline — Twin Falls County, ID

Squash (Winter) Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest August 16 Aug 16 – Oct 11

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

147 days in Twin Falls County

Growing Tips for Squash (Winter) in Twin Falls County

Direct sow Squash (Winter) outdoors after May 10 in Twin Falls County when soil has warmed and frost danger has passed.

Common pests for Squash (Winter) in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Twin Falls County receives only 22" of rain annually. Squash (Winter) needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

Twin Falls County is in Zone 6b with an average last frost of May 10. Plan your Squash (Winter) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Twin Falls County, ID?

Twin Falls County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 4.

🌱

Your Twin Falls County Garden Planner — Free

A 24-page printable planner built for Twin Falls County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Twin Falls County, ID. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.