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When to Plant Snap Peas in Big Horn County, MT

Big Horn County, Montana Zone 5a May

Big Horn County, Montana gardeners: here's your May plan

Welcome to May in Zone 5a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 13
Avg. first frost September 30
Soil temp (4") 39°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Time to transplant snap peas

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Plant snap peas from seed, right in the garden

    Your soil is 39°F — warm enough for these to germinate without babying.

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Snap peas have edible pods with plump, sweet peas inside, combining the best features of snow peas and garden peas. They are a garden favorite for fresh eating.

Big Horn County, Montana is in USDA Zone 5a. The average last spring frost is May 13 and the first fall frost is September 30, giving you a growing season of approximately 140 days.

At an elevation of 5,955 feet, Big Horn County receives approximately 22.5 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Snap Peas to ensure they mature before fall.

Big Horn County, MT (Zone 5a) Short season
140 days
Last Spring Frost May 13
140 growing days
First Fall Frost September 30
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Big Horn County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (9 days to spare)
Start indoors: Mar 13 Transplant: May 22 🍅 Harvest: Jul 17 – Sep 11
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Mar 18 Transplant: May 27 🍅 Harvest: Jul 22 – Sep 16
Safe Start (90%) ✓ Fits season (11 days to spare)
Start indoors: Apr 5 Transplant: Jun 14 🍅 Harvest: Aug 9 – Oct 4

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 Big Horn County

How your county's soil matches Snap Peas's growing requirements.

Soil pH

Your soil pH (6.2–7.6) overlaps with Snap Peas's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Big Horn County is excellent for Snap Peas — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Snap Peas.

How to Plant Snap Peas

1"
Planting Depth
4"
Between Plants
18"
Between Rows

Succession Planting Snap Peas

2
successive plantings in your 140-day season

Sow every 6.3 weeks. Last sowing by Jul 22 to harvest before frost.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 37 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Snap Peas

Snap Peas needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Snap Peas Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 2.9" 0.1" 💧 Light watering
Jun 3" 1.7" 1.3" 💧 Light watering
Jul 3" 2.2" 0.8" 💧 Light watering
Aug 3" 2" 1" 💧 Light watering
Sep 3" 1.8" 1.2" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Snap Peas 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.

Snap Peas needs ~766 GDD — county provides 1,715 GDD Excellent fit

Snap Peas Planting Timeline — Big Horn County, MT

Snap Peas Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 – Apr 1
Transplant Outdoors May 27 May 27 – Jun 10
Direct Sow May 20 May 20 – Jun 10
Harvest July 22 Jul 22 – Sep 16

Plant 1" deep · 4" apart · Rows 18" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

55–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

140 days in Big Horn County

Growing Tips for Snap Peas in Big Horn County

Direct sow Snap Peas outdoors after May 13 in Big Horn County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow in early spring as soon as soil can be worked. Provide a trellis 4-6 feet tall. Harvest when pods are plump and snap cleanly when bent.

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 Snap Peas in Big Horn County, MT?

Big Horn County is in Zone 5a with an average last frost of May 13. Plan your Snap Peas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Big Horn County, MT?

Big Horn County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 13 and first fall frost is September 30.

🌱

Your Big Horn County Garden Planner — Free

A 24-page printable planner built for Big Horn 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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Big Horn County, MT. 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.