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When to Plant Horseradish in Elmore 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.

Elmore County, Idaho is in USDA Zone 6a. The average last spring frost is April 27 and the first fall frost is October 14, giving you a growing season of approximately 170 days.

At an elevation of 5,944 feet, Elmore County receives approximately 20.3 inches of rainfall annually with predominantly loam soil. Summer highs average 88ยฐF, providing good warmth for Horseradish during the growing season.

Elmore County, ID (Zone 6a) Moderate season
170 days
Last Spring Frost April 27
170 growing days
First Fall Frost October 14

Elmore County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Apr 28 🍅 Harvest: Sep 1 – Nov 10
Recommended (50%) ✗ May not fit
Transplant: May 11 🍅 Harvest: Sep 14 – Nov 23
Safe Start (90%) ✗ May not fit
Transplant: Jun 2 🍅 Harvest: Oct 6 – Dec 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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,450 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Horseradish needs ~2,400 GDD — county provides 2,720 GDD Good fit

Horseradish Planting Timeline โ€” Elmore County, ID

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors May 11 May 11 โ€“ May 25
Harvest September 14 Sep 14 โ€“ Nov 23

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 โ€”
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 6a

Growing Season

170 days

Growing Tips for Elmore 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 Elmore County, ID?

Elmore County is in Zone 6a with an average last frost of April 27. Plan your Horseradish planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Elmore County, ID?

Elmore County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is April 27 and first fall frost is October 14.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Elmore County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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