When to Plant Sweet Corn in Lee County, IA
Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.
Lee County, Iowa is in USDA Zone 5b. The average last spring frost is April 16 and the first fall frost is October 18, giving you a growing season of approximately 185 days.
At an elevation of 1,393 feet, Lee County receives approximately 36.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.
Lee County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.2
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.
Soil Compatibility in Lee County
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (6.1–7.2) overlaps with Sweet Corn's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Lee County is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Sweet Corn.
Organic Matter
Organic matter is excellent (4.4%) — Sweet Corn will thrive.
How to Plant Sweet Corn
Succession Planting Sweet Corn
Sow every 6.9 weeks. Last sowing by Jul 20 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Sweet Corn
Sweet Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Sweet Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 6.5" | 3.3" | 3.2" | 💧 Light watering |
| May | 6.5" | 4.2" | 2.3" | 💧 Light watering |
| Jun | 6.5" | 4.3" | 2.2" | 💧 Light watering |
| Jul | 6.5" | 4" | 2.5" | 💧 Light watering |
| Aug | 6.5" | 4.1" | 2.4" | 💧 Light watering |
| Sep | 6.5" | 2.9" | 3.6" | 🚿 Regular watering |
| Oct | 6.5" | 2.9" | 3.6" | 🚿 Regular watering |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Lee County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet Corn 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.
Sweet Corn Planting Timeline — Lee County, IA
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 23 | Apr 23 – May 14 |
| Harvest | June 25 | Jun 25 – Aug 6 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
185 days in Lee County
Growing Tips for Sweet Corn in Lee County
Direct sow Sweet Corn outdoors after April 16 in Lee County when soil has warmed and frost danger has passed.
Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Corn in Other Locations
Frequently Asked Questions
When should I plant Sweet Corn in Lee County, IA?
Lee County is in Zone 5b with an average last frost of April 16. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lee County, IA?
Lee County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 16 and first fall frost is October 18.
Plan Your Garden with Confidence
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