When to Plant Squash (Summer) in St. Clair County, MO
Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.
St. Clair County, Missouri is in USDA Zone 6a. The average last spring frost is April 8 and the first fall frost is October 26, giving you a growing season of approximately 201 days.
At an elevation of 699 feet, St. Clair County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Squash (Summer) during the growing season.
St. Clair County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.7
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
Squash (Summer) Planting Timeline — St. Clair County, MO
Squash (Summer) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 4 | Mar 4 – Mar 18 |
| Transplant Outdoors | April 22 | Apr 22 – May 6 |
| Direct Sow | April 15 | Apr 15 – May 6 |
| Harvest | June 10 | Jun 10 – Aug 12 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| 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 6a
Growing Season
201 days
Growing Tips for St. Clair 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 St. Clair County, MO?
St. Clair County is in Zone 6a with an average last frost of April 8. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Clair County, MO?
St. Clair County, Missouri is in USDA Hardiness Zone 6a. The average last spring frost is April 8 and first fall frost is October 26.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help St. Clair County gardeners in Zone 6a 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.