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When to Plant Peas in Lemhi County, ID

Lemhi County, Idaho Zone 5b May

May in Lemhi County, Idaho — your action list

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

Avg. last frost June 9
Avg. first frost September 14
Soil temp (4") 33°F
Watering High
Pest pressure Low
Daylight 14.6 hrs
  1. Plant peas from seed, right in the garden

    Your soil is 33°F — warm enough for these to germinate without babying.

To set up a strong June, finish these tasks
  • Transplants going out: peas

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Peas are a cool-season legume that fixes nitrogen in the soil. Garden peas are shelled, while snap and snow peas are eaten pod and all.

Lemhi County, Idaho is in USDA Zone 5b. The average last spring frost is June 9 and the first fall frost is September 14, giving you a growing season of approximately 97 days.

At an elevation of 6,743 feet, Lemhi County receives approximately 12.6 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Peas to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Peas successfully. Mulch heavily to conserve soil moisture.

Lemhi County, ID (Zone 5b) Very short season
97 days
Last Spring Frost June 9
97 growing days
First Fall Frost September 14
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Lemhi County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jul 9 – Sep 3
Recommended (50%) ✗ May not fit
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Aug 4 – Sep 29
Safe Start (90%) ✗ May not fit
Start indoors: May 21 Transplant: Jun 25 🍅 Harvest: Aug 20 – Oct 15

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 Lemhi County

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

Soil pH

Your soil pH (6.2–8.2) overlaps with Peas's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Peas

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

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

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.6″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 160 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Peas

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 Peas Needs Rainfall You Supplement Action
Jan 0.8" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 1.4" 0" ❄️ Dormant
Jun 3" 0.8" 2.2" 🚿 Regular watering
Jul 3" 1.3" 1.7" 🚿 Regular watering
Aug 3" 1.3" 1.7" 🚿 Regular watering
Sep 3" 1.2" 1.8" 🚿 Regular watering
Oct 1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

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.

Peas needs ~812 GDD — county provides 1,261 GDD Excellent fit

Peas Planting Timeline — Lemhi County, ID

Peas Planting Calendar

Activity When Date Range
Start Indoors May 5 May 5 – May 19
Transplant Outdoors June 9 Jun 9 – Jun 23
Direct Sow May 26 May 26 – Jun 16
Harvest August 4 Aug 4 – Sep 29
Fall Sowing July 6 Jul 6 – Jul 20

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing
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 5b

📆 Growing Season

97 days in Lemhi County

Growing Tips for Peas in Lemhi County

Direct sow Peas outdoors after June 09 in Lemhi County when soil has warmed and frost danger has passed.

Common pests for 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 as early as soil can be worked in spring. Inoculate seeds with rhizobium for best nitrogen fixation. Provide trellising for climbing varieties.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Peas Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let pods dry brown and papery on the vine.
Storage Store airtight; viable 3 years at 35°F, under 45% humidity.

Very easy to save. Self-pollinating means varieties stay true.

Frequently Asked Questions

When should I plant Peas in Lemhi County, ID?

Lemhi County is in Zone 5b with an average last frost of June 9. Plan your Peas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lemhi County, ID?

Lemhi County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 9 and first fall frost is September 14.

🌱

Your Lemhi County Garden Planner — Free

A 24-page printable planner built for Lemhi County (Zone 5b). 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 Lemhi County, ID. 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.