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When to Plant Corn in Ashland County, WI

Ashland County, Wisconsin Zone 4a May

May in the garden — Ashland County, Wisconsin

May is a pivotal month for Ashland County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 20
Avg. first frost September 27
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
Coming up in June — start thinking about
  • Direct-sowing: corn

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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.

Ashland County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 20 and the first fall frost is September 27, giving you a growing season of approximately 130 days.

At an elevation of 705 feet, Ashland County receives approximately 30.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Corn to ensure they mature before fall.

Ashland County, WI (Zone 4a) Short season
130 days
Last Spring Frost May 20
130 growing days
First Fall Frost September 27

Ashland County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Transplant: May 17 🍅 Harvest: Jul 19 – Sep 13
Recommended (50%) ✓ Fits season (11 days to spare)
Transplant: May 20 🍅 Harvest: Jul 22 – Sep 16
Safe Start (90%) ✓ Fits season (9 days to spare)
Transplant: Jun 4 🍅 Harvest: Aug 6 – Oct 1

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 Ashland County

How your county's soil matches Corn's growing requirements.

Soil pH

Your soil pH (6.0–7.0) is within Corn's preferred range (6.0–7.0).

Soil Texture

The silt loam soil in Ashland County is excellent for Corn — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.9%) — Corn will thrive.

How to Plant Corn

1"
Planting Depth
12"
Between Plants
36"
Between Rows

Succession Planting Corn

2
successive plantings in your 130-day season

Sow every 6.9 weeks. Last sowing by Jun 19 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 588 gal / 100 sq ft

Monthly Watering Guide for Corn

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 Corn Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 6.5" 3.8" 2.7" 💧 Light watering
Jun 6.5" 3.8" 2.7" 💧 Light watering
Jul 6.5" 2.9" 3.6" 🚿 Regular watering
Aug 6.5" 3.6" 2.9" 💧 Light watering
Sep 6.5" 2.3" 4.2" 🚿 Regular watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Ashland County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

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.

Corn needs ~740 GDD — county provides 1,202 GDD Excellent fit

Corn Planting Timeline — Ashland County, WI

Corn Planting Calendar

Activity When Date Range
Direct Sow June 3 Jun 3 – Jun 24
Harvest August 5 Aug 5 – Sep 30

Plant 1" deep · 12" apart · Rows 36" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Direct Sow
July
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

60–100 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

130 days in Ashland County

Growing Tips for Corn in Ashland County

Direct sow Corn outdoors after May 20 in Ashland County when soil has warmed and frost danger has passed.

Common pests for 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 rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.

Recommended Corn Varieties for Ashland County

Ultra-early corn varieties for your season

Earlivee (58d) Sugar Buns (72d) Early Sunglow (63d)

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Celery

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Corn in Ashland County, WI?

Ashland County is in Zone 4a with an average last frost of May 20. Plan your Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ashland County, WI?

Ashland County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 20 and first fall frost is September 27.

🌱

Your Ashland County Garden Planner — Free

A 24-page printable planner built for Ashland County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Ashland County, WI. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.