When to Plant Squash (Summer) in Harrison County, IA
Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.
Harrison County, Iowa is in USDA Zone 5a. The average last spring frost is April 24 and the first fall frost is October 10, giving you a growing season of approximately 169 days.
At an elevation of 1,345 feet, Harrison County receives approximately 35.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Squash (Summer) to ensure they mature before fall.
Harrison County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.2
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.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Squash (Summer) Planting Timeline — Harrison County, IA
Squash (Summer) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 20 | Mar 20 – Apr 3 |
| Transplant Outdoors | May 8 | May 8 – May 22 |
| Direct Sow | May 1 | May 1 – May 22 |
| Harvest | June 26 | Jun 26 – Aug 28 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
45–65 days
Soil pH
6 – 7.5
USDA Zone
Zone 5a
Growing Season
169 days
Growing Tips for Harrison County
Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Squash (Summer) in Other Locations
Frequently Asked Questions
When should I plant Squash (Summer) in Harrison County, IA?
Harrison County is in Zone 5a with an average last frost of April 24. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harrison County, IA?
Harrison County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 24 and first fall frost is October 10.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Harrison County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.