When to Plant Lima Beans in O'Brien County, IA
Lima beans are a warm-season legume producing large, creamy beans with a buttery texture. Both bush and pole varieties are available, with pole types yielding more.
O'Brien County, Iowa is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 5, giving you a growing season of approximately 157 days.
At an elevation of 658 feet, O'Brien County receives approximately 40.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Lima Beans to ensure they mature before fall.
O'Brien County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.2
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 O'Brien County
How your county's soil matches Lima Beans's growing requirements.
Soil pH
Your soil pH (5.8–7.2) overlaps with Lima Beans's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in O'Brien County is excellent for Lima Beans — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Lima Beans will thrive.
How to Plant Lima Beans
Succession Planting Lima Beans
Sow every 6.9 weeks. Last sowing by Jul 07 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Lima Beans
Lima Beans needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.
| Month | Lima Beans Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | — | 3.8" | 0" | ❄️ Dormant |
| May | 3.9" | 5.1" | 0" | ✅ Rainfall sufficient |
| Jun | 3.9" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jul | 3.9" | 4.5" | 0" | ✅ Rainfall sufficient |
| Aug | 3.9" | 4.8" | 0" | ✅ Rainfall sufficient |
| Sep | 3.9" | 3.2" | 0.7" | 💧 Light watering |
| Oct | 3.9" | 3.6" | 0.3" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in O'Brien County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Lima 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.
Lima Beans Planting Timeline — O'Brien County, IA
Lima Beans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 15 | May 15 – Jun 5 |
| Harvest | July 17 | Jul 17 – Aug 28 |
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 | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
157 days in O'Brien County
Growing Tips for Lima Beans in O'Brien County
Direct sow Lima Beans outdoors after May 01 in O'Brien County when soil has warmed and frost danger has passed.
Common pests for Lima 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 soil is thoroughly warm at 65F or above. Do not soak seeds before planting as they may crack. Harvest when pods are plump but still green for fresh limas.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Lima Beans in Other Locations
Frequently Asked Questions
When should I plant Lima Beans in O'Brien County, IA?
O'Brien County is in Zone 4b with an average last frost of May 1. Plan your Lima Beans planting based on this frost date — see the calendar above for exact timing.
What planting zone is O'Brien County, IA?
O'Brien County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 5.
Plan Your Garden with Confidence
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