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When to Plant Spaghetti Squash in Union County, OR

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

Union County, Oregon is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.

At an elevation of 2,751 feet, Union County receives approximately 23.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Spaghetti Squash during the growing season.

Union County, OR (Zone 5b) Short season
137 days
Last Spring Frost May 12
137 growing days
First Fall Frost September 26

Union County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (1 days to spare)
Start indoors: Mar 29 Transplant: May 17 🍅 Harvest: Aug 16 – Sep 13
Recommended (50%) ✓ Fits season (4 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Aug 25 – Sep 22
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: May 4 Transplant: Jun 22 🍅 Harvest: Sep 21 – Oct 19

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
0.6″/week
Watering frequency 1-2 times/week
Season total 707 gal / 100 sq ft
Spaghetti Squash needs ~1,341 GDD — county provides 1,986 GDD Excellent fit

Spaghetti Squash Planting Timeline โ€” Union County, OR

Spaghetti Squash Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 โ€“ Apr 21
Transplant Outdoors May 26 May 26 โ€“ Jun 9
Direct Sow May 19 May 19 โ€“ Jun 9
Harvest August 25 Aug 25 โ€“ Sep 22

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 Transplant Outdoors 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 5b

Growing Season

137 days

Growing Tips for Union 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Spaghetti Squash in Union County, OR?

Union County is in Zone 5b with an average last frost of May 12. Plan your Spaghetti Squash planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Union County, OR?

Union County, Oregon is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is September 26.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Union 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 Union County, OR. Local conditions may vary. Last updated: April 2026.