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When to Plant Pole Beans in Prairie County, MT

Pole beans are climbing varieties of green beans that produce over a much longer season than bush types. They require trellising but yield more per square foot.

Prairie County, Montana is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is October 1, giving you a growing season of approximately 143 days.

At an elevation of 6,830 feet, Prairie County receives approximately 22.2 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Pole Beans to ensure they mature before fall.

Prairie County, MT (Zone 4a) Short season
143 days
Last Spring Frost May 11
143 growing days
First Fall Frost October 1

Prairie County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (9 days to spare)
Start indoors: Mar 3 Transplant: May 26 🍅 Harvest: Jul 21 – Sep 15
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Mar 9 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 21
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: Mar 21 Transplant: Jun 13 🍅 Harvest: Aug 8 – Oct 3

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 Prairie County

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

Soil pH

Your soil pH (6.7โ€“7.8) is more alkaline than Pole Beans prefers (6.0โ€“7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Prairie County is excellent for Pole Beans โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Pole Beans.

How to Plant Pole Beans

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

Succession Planting Pole Beans

3
successive plantings in your 143-day season

Sow every 6.3 weeks. Last sowing by Jul 23 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 531 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Monthly Watering Guide for Pole Beans

Pole 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 Pole Beans Needs Rainfall You Supplement Action
Jan โ€” 1.7" 0" โ„๏ธ Dormant
Feb โ€” 1.4" 0" โ„๏ธ Dormant
Mar โ€” 1.8" 0" โ„๏ธ Dormant
Apr โ€” 2.3" 0" โ„๏ธ Dormant
May 4.3" 3" 1.3" ๐Ÿ’ง Light watering
Jun 4.3" 1.6" 2.7" ๐Ÿšฟ Regular watering
Jul 4.3" 1.7" 2.6" ๐Ÿšฟ Regular watering
Aug 4.3" 2.3" 2" ๐Ÿ’ง Light watering
Sep 4.3" 1.7" 2.6" ๐Ÿšฟ Regular watering
Oct 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Nov โ€” 1.7" 0" โ„๏ธ Dormant
Dec โ€” 1.2" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Oct in Prairie County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Pole 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" โ€” every day above 50ยฐF 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.

Pole Beans needs ~672 GDD — county provides 1,537 GDD Excellent fit

Pole Beans Planting Timeline โ€” Prairie County, MT

Pole Beans Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 โ€“ Mar 23
Transplant Outdoors June 1 Jun 1 โ€“ Jun 15
Direct Sow May 25 May 25 โ€“ Jun 15
Harvest July 27 Jul 27 โ€“ Sep 21

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April โ€”
May Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท 1-2 times/week

๐Ÿ“… Days to Maturity

55โ€“70 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: too_alkaline

๐Ÿ—บ๏ธ USDA Zone

Zone 4a

๐Ÿ“† Growing Season

143 days in Prairie County

Growing Tips for Pole Beans in Prairie County

Direct sow Pole Beans outdoors after May 11 in Prairie County when soil has warmed and frost danger has passed.

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

Prairie County receives only 22" of rain annually. Pole Beans needs consistent moisture โ€” install drip irrigation or water deeply 2-3 times per week.

General growing tips

Provide sturdy 6-8 foot poles, tepees, or trellises. Direct sow after last frost. Pick regularly to encourage continued production. Beans fix nitrogen benefiting following crops.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic
  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pole Beans in Prairie County, MT?

Prairie County is in Zone 4a with an average last frost of May 11. Plan your Pole Beans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Prairie County, MT?

Prairie County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Prairie County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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