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When to Plant Horseradish in Inyo County, CA

Inyo County, California Zone 8b May

May in Inyo County, California — your action list

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Avg. last frost January 15
Avg. first frost December 10
Soil temp (4") 57°F
Watering Critical
Pest pressure Moderate
Daylight 13.9 hrs
Before June arrives, get these ready
  • First harvests: horseradish

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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.

Inyo County, California is in USDA Zone 8b. The average last spring frost is January 15 and the first fall frost is December 10, giving you a growing season of approximately 329 days.

At an elevation of 4,562 feet, Inyo County receives approximately 16.4 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Horseradish during the growing season. With low rainfall, drip irrigation is essential for growing Horseradish successfully. Mulch heavily to conserve soil moisture.

Inyo County, CA (Zone 8b) Year-round
329 days
Last Spring Frost January 15
329 growing days
First Fall Frost December 10
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Inyo County Soil Profile

Soil Type

Loam

Soil pH

6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (122 days to spare)
Transplant: Jan 21 🍅 Harvest: May 27 – Aug 5
Recommended (50%) ✓ Fits season (119 days to spare)
Transplant: Jan 29 🍅 Harvest: Jun 4 – Aug 13
Safe Start (90%) ✓ Fits season (105 days to spare)
Transplant: Feb 23 🍅 Harvest: Jun 29 – Sep 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 Inyo County

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

Soil pH

Your soil pH (6.0–7.8) overlaps with Horseradish's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Inyo County is excellent for Horseradish — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Horseradish.

How to Plant Horseradish

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,789 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Horseradish

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

Month Horseradish Needs Rainfall You Supplement Action
Jan 4.3" 3.3" 1" 💧 Light watering
Feb 4.3" 3.4" 0.9" 💧 Light watering
Mar 4.3" 2.5" 1.8" 💧 Light watering
Apr 4.3" 1.3" 3" 🚿 Regular watering
May 4.3" 0.5" 3.8" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.6" 3.7" 🚿 Regular watering
Nov 4.3" 1.7" 2.6" 🚿 Regular watering
Dec 4.3" 2.8" 1.5" 💧 Light watering

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

Horseradish 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.

Horseradish needs ~2,400 GDD — county provides 5,280 GDD Excellent fit

Horseradish Planting Timeline — Inyo County, CA

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors January 29 Jan 29 – Feb 12
Harvest June 4 Jun 4 – Aug 13

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

Month-by-Month Timeline

MonthActivities
January Transplant Outdoors
February Transplant Outdoors
March
April
May
June Harvest
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

329 days in Inyo County

Growing Tips for Horseradish in Inyo County

Direct sow Horseradish outdoors after January 15 in Inyo County when soil has warmed and frost danger has passed.

Common pests for Horseradish in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Inyo County receives only 16" of rain annually. Horseradish needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Horseradish in Inyo County, CA?

Inyo County is in Zone 8b with an average last frost of January 15. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Inyo County, CA?

Inyo County, California is in USDA Hardiness Zone 8b. The average last spring frost is January 15 and first fall frost is December 10.

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Your Inyo County Garden Planner — Free

A 24-page printable planner built for Inyo County (Zone 8b). 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 Inyo County, CA. 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.