When to Plant Corn in San Joaquin County, CA
Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.
San Joaquin County, California is in USDA Zone 9a. The average last spring frost is February 4 and the first fall frost is December 6, giving you a growing season of approximately 305 days.
At an elevation of 220 feet, San Joaquin County receives approximately 15 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Corn during the growing season. With low rainfall, drip irrigation is essential for growing Corn successfully. Mulch heavily to conserve soil moisture.
San Joaquin County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.8
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 8/10 — consider drought-tolerant varieties and mulching
Corn Planting Timeline — San Joaquin County, CA
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | February 11 | Feb 11 – Mar 4 |
| Harvest | April 15 | Apr 15 – Jun 10 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Direct Sow |
| March | Direct Sow |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
60–100 days
Soil pH
6 – 7
USDA Zone
Zone 9a
Growing Season
305 days
Growing Tips for San Joaquin County
Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Corn in Other Locations
Frequently Asked Questions
When should I plant Corn in San Joaquin County, CA?
San Joaquin County is in Zone 9a with an average last frost of February 4. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Joaquin County, CA?
San Joaquin County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 4 and first fall frost is December 6.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help San Joaquin County gardeners in Zone 9a 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.