When to Plant Black Beans in Marathon County, WI
Your May game plan for Marathon County, Wisconsin
May is a pivotal month for Marathon County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Seed black beans outdoors
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
Black beans are a warm-season legume producing small, dark, protein-rich beans that are a staple in Latin American and Caribbean cuisines.
Marathon County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 2, giving you a growing season of approximately 144 days.
At an elevation of 723 feet, Marathon County receives approximately 39.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Black Beans to ensure they mature before fall.
Marathon County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.3
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 Marathon County
How your county's soil matches Black Beans's growing requirements.
Soil pH
Your soil pH (6.0–7.3) is within Black Beans's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Marathon County is excellent for Black Beans — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Black Beans will thrive.
How to Plant Black Beans
Plant Water Budget
Monthly Watering Guide for Black Beans
Black 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 | Black Beans Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 2" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | — | 4.3" | 0" | ❄️ Dormant |
| May | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | 4.3" | 3" | 1.3" | 💧 Light watering |
| Nov | — | 2.4" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Marathon County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Black 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.
Black Beans Planting Timeline — Marathon County, WI
Black Beans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 25 | May 25 – Jun 15 |
| Harvest | August 24 | Aug 24 – Oct 12 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 4b
📆 Growing Season
144 days in Marathon County
Growing Tips for Black Beans in Marathon County
Direct sow Black Beans outdoors after May 11 in Marathon County when soil has warmed and frost danger has passed.
Common pests for Black 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 after last frost. Provide support for climbing varieties. Allow pods to dry fully on the vine before harvesting. Thresh dried pods by hand or in a pillowcase.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Black Beans in Other Locations
Frequently Asked Questions
When should I plant Black Beans in Marathon County, WI?
Marathon County is in Zone 4b with an average last frost of May 11. Plan your Black Beans planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marathon County, WI?
Marathon County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 2.
Your Marathon County Garden Planner — Free
A 24-page printable planner built for Marathon County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.