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When to Plant Horseradish in Amador County, CA

Amador County, California Zone 9b May

May to-do list for Amador County, California

May is a pivotal month for Amador County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost March 8
Avg. first frost November 25
Soil temp (4") 69°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs

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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.

Amador County, California is in USDA Zone 9b. The average last spring frost is March 8 and the first fall frost is November 25, giving you a growing season of approximately 262 days.

At an elevation of 1,335 feet, Amador County receives approximately 42.7 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Horseradish during the growing season.

Amador County, CA (Zone 9b) Long season
262 days
Last Spring Frost March 8
262 growing days
First Fall Frost November 25
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Amador County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (67 days to spare)
Transplant: Feb 19 🍅 Harvest: Jun 25 – Sep 3
Recommended (50%) ✓ Fits season (52 days to spare)
Transplant: Mar 22 🍅 Harvest: Jul 26 – Oct 4
Safe Start (90%) ✓ Fits season (34 days to spare)
Transplant: May 3 🍅 Harvest: Sep 6 – Nov 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.

Soil Compatibility in Amador County

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

Soil pH

Your soil pH (6.7–7.8) overlaps with Horseradish's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). 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
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 883 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 9.4" 0" ❄️ Dormant
Feb 8" 0" ❄️ Dormant
Mar 4.3" 6" 0" ✅ Rainfall sufficient
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 1" 3.3" 🚿 Regular watering
Jun 4.3" 0.2" 4.1" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.5" 3.8" 🚿 Regular watering
Oct 4.3" 1.9" 2.4" 🚿 Regular watering
Nov 4.3" 4.3" 0" ✅ Rainfall sufficient
Dec 7.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Amador 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 ~2,512 GDD — county provides 4,388 GDD Excellent fit

Horseradish Planting Timeline — Amador County, CA

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors March 22 Mar 22 – Apr 5
Harvest July 26 Jul 26 – Oct 4

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

262 days in Amador County

Growing Tips for Horseradish in Amador County

Direct sow Horseradish outdoors after March 08 in Amador 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.

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 Amador County, CA?

Amador County is in Zone 9b with an average last frost of March 8. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Amador County, CA?

Amador County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 8 and first fall frost is November 25.

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Your Amador County Garden Planner — Free

A 24-page printable planner built for Amador County (Zone 9b). 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 Amador 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.