When to Plant Sweet Corn in Clearwater County, MN
May to-do list for Clearwater County, Minnesota
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Plant sweet corn from seed, right in the garden
Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.
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.
Clearwater County, Minnesota is in USDA Zone 3b. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.
At an elevation of 1,074 feet, Clearwater County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.
Clearwater County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.2
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 Clearwater County
How your county's soil matches Sweet Corn's growing requirements.
Soil pH
Your soil pH (6.2–7.2) overlaps with Sweet Corn's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Clearwater 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 (4.6%) — Sweet Corn will thrive.
How to Plant Sweet Corn
Succession Planting Sweet Corn
Sow every 6.9 weeks. Last sowing by Jun 30 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.8" | 0" | ❄️ Dormant |
| May | 6.5" | 4.2" | 2.3" | 💧 Light watering |
| Jun | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Jul | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Aug | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Sep | 6.5" | 3.3" | 3.2" | 💧 Light watering |
| Oct | — | 2.5" | 0" | ❄️ Dormant |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Clearwater 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 — Clearwater County, MN
Sweet Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 29 | May 29 – Jun 19 |
| Harvest | July 31 | Jul 31 – Sep 11 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| 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 3b
📆 Growing Season
136 days in Clearwater County
Growing Tips for Sweet Corn in Clearwater County
Direct sow Sweet Corn outdoors after May 15 in Clearwater 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 Clearwater County, MN?
Clearwater County is in Zone 3b with an average last frost of May 15. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clearwater County, MN?
Clearwater County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 15 and first fall frost is September 28.
Your Clearwater County Garden Planner — Free
A 24-page printable planner built for Clearwater County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.