When to Plant Horseradish in Custer 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.
Custer County, Idaho is in USDA Zone 4a. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.
At an elevation of 5,189 feet, Custer County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Horseradish to ensure they mature before fall.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
Drainage
Well Drained
Plant Planting Risk Windows
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
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Horseradish Planting Timeline — Custer County, ID
Horseradish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | July 2 | Jul 2 – Jul 16 |
| Harvest | November 5 | Nov 5 – Nov 26 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | Transplant Outdoors |
| August | — |
| September | — |
| October | — |
| November | Harvest |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
120–180 days
Soil pH
6 – 7.5
USDA Zone
Zone 4a
Growing Season
79 days
Growing Tips for Custer 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
Horseradish in Other Locations
Frequently Asked Questions
When should I plant Horseradish in Custer County, ID?
Custer County is in Zone 4a with an average last frost of June 18. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Custer County, ID?
Custer County, Idaho is in USDA Hardiness Zone 4a. The average last spring frost is June 18 and first fall frost is September 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Custer County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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