When to Plant Acorn Squash in Union County, IA
Acorn squash is a small winter squash with dark green, ribbed skin and mildly sweet orange flesh. It is perfect for stuffing and roasting as individual servings.
Union County, Iowa is in USDA Zone 5a. The average last spring frost is April 23 and the first fall frost is October 11, giving you a growing season of approximately 171 days.
At an elevation of 1,311 feet, Union County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Acorn Squash to ensure they mature before fall.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-7.3
Drainage
Well Drained
Plant Planting Risk Windows
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 Union County
How your county's soil matches Acorn Squash's growing requirements.
Soil pH
Your soil pH (6.3–7.3) overlaps with Acorn Squash's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Union County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Acorn Squash will thrive.
How to Plant Acorn Squash
Succession Planting Acorn Squash
Sow every 9.1 weeks. Last sowing by Jul 03 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Acorn Squash
Acorn Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.
| Month | Acorn Squash Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 4.8" | 4.1" | 0.7" | 💧 Light watering |
| May | 4.8" | 4.1" | 0.7" | 💧 Light watering |
| Jun | 4.8" | 4.7" | 0.1" | 💧 Light watering |
| Jul | 4.8" | 4.2" | 0.6" | 💧 Light watering |
| Aug | 4.8" | 4" | 0.8" | 💧 Light watering |
| Sep | 4.8" | 3.4" | 1.4" | 💧 Light watering |
| Oct | 4.8" | 3" | 1.8" | 💧 Light watering |
| Nov | — | 2.8" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Union County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Acorn Squash 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.
Acorn Squash Planting Timeline — Union County, IA
Acorn Squash Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 19 | Mar 19 – Apr 2 |
| Transplant Outdoors | May 7 | May 7 – May 21 |
| Direct Sow | April 30 | Apr 30 – May 21 |
| Harvest | July 30 | Jul 30 – Sep 3 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.1"/week · Only during dry spells
📅 Days to Maturity
80–100 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
171 days in Union County
Growing Tips for Acorn Squash in Union County
Direct sow Acorn Squash outdoors after April 23 in Union County when soil has warmed and frost danger has passed.
Common pests for Acorn Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow after last frost. Harvest when the ground spot turns orange and the skin is hard. Acorn squash has a shorter storage life than butternut, lasting about 2 months.
Companion Planting
Good Companions
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Acorn Squash in Other Locations
Frequently Asked Questions
When should I plant Acorn Squash in Union County, IA?
Union County is in Zone 5a with an average last frost of April 23. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, IA?
Union County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 23 and first fall frost is October 11.
Plan Your Garden with Confidence
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