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When to Plant Potatoes in Clark County, ID

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

Clark County, Idaho is in USDA Zone 4a. The average last spring frost is June 7 and the first fall frost is September 10, giving you a growing season of approximately 95 days.

At an elevation of 7,493 feet, Clark County receives approximately 21.9 inches of rainfall annually with predominantly loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Potatoes to ensure they mature before fall.

Clark County, ID (Zone 4a) Very short season
95 days
Last Spring Frost June 7
95 growing days
First Fall Frost September 10

Clark County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 21 Transplant: Jun 13 🍅 Harvest: Aug 22 – Oct 31
Recommended (50%) ✗ May not fit
Start indoors: Apr 5 Transplant: Jun 28 🍅 Harvest: Sep 6 – Nov 15
Safe Start (90%) ✗ May not fit
Start indoors: Apr 19 Transplant: Jul 12 🍅 Harvest: Sep 20 – Nov 29

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 32 gal / 100 sq ft
Drought risk

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

Potatoes needs ~1,092 GDD — county provides 1,092 GDD Tight fit

Potatoes Planting Timeline โ€” Clark County, ID

Potatoes Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 โ€“ Apr 19
Transplant Outdoors June 28 Jun 28 โ€“ Jul 12
Direct Sow June 21 Jun 21 โ€“ Jul 12
Harvest September 6 Sep 6 โ€“ Nov 15

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

70โ€“120 days

Soil pH

5 โ€“ 6.5

USDA Zone

Zone 4a

Growing Season

95 days

Growing Tips for Clark County

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.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Cucumber
  • Squash Summer

Level Up Your Garden

Frequently Asked Questions

When should I plant Potatoes in Clark County, ID?

Clark County is in Zone 4a with an average last frost of June 7. Plan your Potatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clark County, ID?

Clark County, Idaho is in USDA Hardiness Zone 4a. The average last spring frost is June 7 and first fall frost is September 10.

๐ŸŒฑ

Plan Your Garden with Confidence

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

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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 Clark County, ID. Local conditions may vary. Last updated: April 2026.