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When to Plant Fava Beans in Iowa County, WI

Iowa County, Wisconsin Zone 5a May

What to do in May

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

Avg. last frost May 3
Avg. first frost October 7
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Time to transplant fava beans

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

June prep starts now
  • Starting indoors: fava beans

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Fava beans are a cool-season legume with large, meaty beans inside thick pods. They fix nitrogen in the soil and are one of the oldest cultivated crops.

Iowa County, Wisconsin is in USDA Zone 5a. The average last spring frost is May 3 and the first fall frost is October 7, giving you a growing season of approximately 157 days.

At an elevation of 602 feet, Iowa County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Fava Beans to ensure they mature before fall.

Iowa County, WI (Zone 5a) Moderate season
157 days
Last Spring Frost May 3
157 growing days
First Fall Frost October 7
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Iowa County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jul 13 – Aug 24
Recommended (50%) ✓ Fits season (38 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jul 19 – Aug 30
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Aug 6 – Sep 17

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 Iowa County

How your county's soil matches Fava Beans's growing requirements.

Soil pH

Your soil pH (5.8–7.1) overlaps with Fava Beans's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Fava Beans.

How to Plant Fava Beans

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Fava Beans

2
successive plantings in your 157-day season

Sow every 8.6 weeks. Last sowing by Jun 29 to harvest before frost.

For a dedicated fall crop, sow by Jul 29.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 55 gal / 100 sq ft

Monthly Watering Guide for Fava Beans

Fava Beans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Fava Beans Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 4.3" 4" 0.3" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.7" 0.6" 💧 Light watering
Aug 4.3" 3.6" 0.7" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

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

Fava Beans 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.

Fava Beans needs ~1,006 GDD — county provides 1,805 GDD Excellent fit

Fava Beans Planting Timeline — Iowa County, WI

Fava Beans Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 3 May 3 – May 17
Direct Sow April 19 Apr 19 – May 10
Harvest July 19 Jul 19 – Aug 30
Fall Sowing July 29 Jul 29 – Aug 12

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Fall Sowing Harvest
August Fall Sowing Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

75–100 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

157 days in Iowa County

Growing Tips for Fava Beans in Iowa County

Direct sow Fava Beans outdoors after May 03 in Iowa County when soil has warmed and frost danger has passed.

Common pests for Fava Beans in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow as early as soil can be worked in spring. Pinch growing tips when pods begin to form to redirect energy and reduce aphid problems. Stake tall varieties.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Fava Beans in Iowa County, WI?

Iowa County is in Zone 5a with an average last frost of May 3. Plan your Fava Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Iowa County, WI?

Iowa County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is May 3 and first fall frost is October 7.

🌱

Your Iowa County Garden Planner — Free

A 24-page printable planner built for Iowa County (Zone 5a). 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 Iowa 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.