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When to Plant Horseradish in Minidoka County, ID

Horseradish is a vigorous perennial grown for its pungent, spicy roots used as a condiment. Once established, it can be difficult to eradicate, so choose its location carefully.

Minidoka County, Idaho is in USDA Zone 5b. The average last spring frost is May 10 and the first fall frost is October 3, giving you a growing season of approximately 146 days.

At an elevation of 5,990 feet, Minidoka County receives approximately 22.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Horseradish during the growing season.

Minidoka County, ID (Zone 5b) Short season
146 days
Last Spring Frost May 10
146 growing days
First Fall Frost October 3

Minidoka County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 15 🍅 Harvest: Sep 18 – Oct 30
Recommended (50%) ✗ May not fit
Transplant: May 24 🍅 Harvest: Sep 27 – Nov 8
Safe Start (90%) ✗ May not fit
Transplant: Jun 20 🍅 Harvest: Oct 24 – Dec 5

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
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 559 gal / 100 sq ft
Drought risk

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

Horseradish needs ~2,175 GDD — county provides 2,117 GDD Tight fit

Horseradish Planting Timeline โ€” Minidoka County, ID

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors May 24 May 24 โ€“ Jun 7
Harvest September 27 Sep 27 โ€“ Nov 8

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June Transplant Outdoors
July โ€”
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

120โ€“180 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

146 days

Growing Tips for Minidoka County

Plant root cuttings at a 45-degree angle in early spring. Harvest roots in late fall for strongest flavor. Contain the plant with barriers or grow in large containers.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Horseradish in Minidoka County, ID?

Minidoka County is in Zone 5b with an average last frost of May 10. Plan your Horseradish planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Minidoka County, ID?

Minidoka County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 10 and first fall frost is October 3.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Minidoka County gardeners in Zone 5b 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 Minidoka County, ID. Local conditions may vary. Last updated: April 2026.