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When to Plant Spaghetti Squash in Dewey County, SD

Spaghetti squash is a winter squash whose cooked flesh separates into pasta-like strands. It is a popular low-carb alternative to pasta.

Dewey County, South Dakota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is October 3, giving you a growing season of approximately 145 days.

At an elevation of 1,004 feet, Dewey County receives approximately 25.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Spaghetti Squash to ensure they mature before fall.

Dewey County, SD (Zone 4a) Short season
145 days
Last Spring Frost May 11
145 growing days
First Fall Frost October 3

Dewey County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 21 Transplant: May 23 🍅 Harvest: Aug 22 – Sep 19
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Mar 30 Transplant: Jun 1 🍅 Harvest: Aug 31 – Sep 28
Safe Start (90%) ✓ Fits season (10 days to spare)
Start indoors: Apr 7 Transplant: Jun 9 🍅 Harvest: Sep 8 – Oct 6

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
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 418 gal / 100 sq ft
Drought risk

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

Spaghetti Squash needs ~1,202 GDD — county provides 1,885 GDD Excellent fit

Spaghetti Squash Planting Timeline โ€” Dewey County, SD

Spaghetti Squash Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors June 1 Jun 1 โ€“ Jun 15
Direct Sow May 25 May 25 โ€“ Jun 15
Harvest August 31 Aug 31 โ€“ Sep 28

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

85โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

145 days

Growing Tips for Dewey County

Direct sow on mounds after last frost. Harvest when skin turns golden yellow and is hard. Store in a cool, dry place for 2-3 months. Bake or microwave halves until tender.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

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Frequently Asked Questions

When should I plant Spaghetti Squash in Dewey County, SD?

Dewey County is in Zone 4a with an average last frost of May 11. Plan your Spaghetti Squash planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Dewey County, SD?

Dewey County, South Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is October 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Dewey County gardeners in Zone 4a 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 Dewey County, SD. Local conditions may vary. Last updated: April 2026.