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When to Plant Potatoes in Nez Perce County, ID

Nez Perce County, Idaho Zone 7b May

Nez Perce County, Idaho gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Nez Perce County, Idaho this May and put them front and centre. Tackle them in order.

Avg. last frost May 12
Avg. first frost September 26
Soil temp (4") 48°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Set out potatoes seedlings

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

  2. Scatter potatoes into prepared beds

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

A few tasks this May that'll pay off in June
  • Starting indoors: potatoes

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Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.

Nez Perce County, Idaho is in USDA Zone 7b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.

At an elevation of 4,819 feet, Nez Perce County receives approximately 16.7 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Potatoes during the growing season. With low rainfall, drip irrigation is essential for growing Potatoes successfully. Mulch heavily to conserve soil moisture.

Nez Perce County, ID (Zone 7b) Short season
137 days
Last Spring Frost May 12
137 growing days
First Fall Frost September 26

Nez Perce County Soil Profile

Soil Type

Loam

Soil pH

6.6-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Jul 30 – Oct 8
Recommended (50%) ✗ May not fit
Start indoors: Mar 24 Transplant: May 26 🍅 Harvest: Aug 4 – Oct 13
Safe Start (90%) ✗ May not fit
Start indoors: Apr 18 Transplant: Jun 20 🍅 Harvest: Aug 29 – Nov 7

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 Nez Perce County

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

Soil pH

Your soil pH (6.6–8.0) is more alkaline than Potatoes prefers (5.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Nez Perce County is excellent for Potatoes — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Potatoes.

How to Plant Potatoes

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

Succession Planting Potatoes

2
successive plantings in your 137-day season

Sow every 8 weeks. Last sowing by May 29 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 714 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Potatoes

Potatoes needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Potatoes Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 4.3" 1.8" 2.5" 🚿 Regular watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.5" 2.8" 🚿 Regular watering
Aug 4.3" 1.7" 2.6" 🚿 Regular watering
Sep 4.3" 1.2" 3.1" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

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

Potatoes 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.

Potatoes needs ~1,662 GDD — county provides 2,397 GDD Excellent fit

Potatoes Planting Timeline — Nez Perce County, ID

Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 – Apr 7
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest August 4 Aug 4 – Oct 13

Plant 1" deep · 15" apart · Rows 24" 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
August Harvest
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

70–120 days

🧪 Soil pH

Needs 5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7b

📆 Growing Season

137 days in Nez Perce County

Growing Tips for Potatoes in Nez Perce County

Direct sow Potatoes outdoors after May 12 in Nez Perce County when soil has warmed and frost danger has passed.

Common pests for Potatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

Nez Perce County receives only 17" of rain annually. Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.

Recommended Potatoes Varieties for Nez Perce County

Early-maturing potatoes for your season

Yukon Gold (65d) Red Norland (70d) Irish Cobbler (70d)

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Cucumber
  • Squash Summer

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Potatoes in Nez Perce County, ID?

Nez Perce County is in Zone 7b with an average last frost of May 12. Plan your Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Nez Perce County, ID?

Nez Perce County, Idaho is in USDA Hardiness Zone 7b. The average last spring frost is May 12 and first fall frost is September 26.

🌱

Your Nez Perce County Garden Planner — Free

A 24-page printable planner built for Nez Perce County (Zone 7b). 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 Nez Perce 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.