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When to Plant Horseradish in Clarion County, PA

Clarion County, Pennsylvania Zone 6a May

Top priorities for Clarion County, Pennsylvania gardeners in May

Your Clarion County, Pennsylvania garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 9
Avg. first frost October 15
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.3 hrs
  1. Transplant horseradish outside

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

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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.

Clarion County, Pennsylvania is in USDA Zone 6a. The average last spring frost is May 9 and the first fall frost is October 15, giving you a growing season of approximately 159 days.

At an elevation of 840 feet, Clarion County receives approximately 44.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Horseradish to ensure they mature before fall.

Clarion County, PA (Zone 6a) Moderate season
159 days
Last Spring Frost May 9
159 growing days
First Fall Frost October 15

Clarion County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 14 🍅 Harvest: Sep 17 – Nov 26
Recommended (50%) ✗ May not fit
Transplant: May 23 🍅 Harvest: Sep 26 – Dec 5
Safe Start (90%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Oct 13 – Dec 22

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 Clarion County

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

Soil pH

Your soil pH (4.8–6.8) is more acidic than Horseradish prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). 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
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 3" 0" ❄️ Dormant
Feb 3.5" 0" ❄️ Dormant
Mar 4" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 3.9" 0.4" 💧 Light watering
Jul 4.3" 4.7" 0" ✅ Rainfall sufficient
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 4.4" 0" ✅ Rainfall sufficient
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 3.2" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Clarion 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 ~1,950 GDD — county provides 2,067 GDD Good fit

Horseradish Planting Timeline — Clarion County, PA

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors May 23 May 23 – Jun 6
Harvest September 26 Sep 26 – Dec 5

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

159 days in Clarion County

Growing Tips for Horseradish in Clarion County

Direct sow Horseradish outdoors after May 09 in Clarion County when soil has warmed and frost danger has passed.

Your 159.0-day growing season in Clarion County is tight for Horseradish (120.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Clarion County, PA?

Clarion County is in Zone 6a with an average last frost of May 9. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clarion County, PA?

Clarion County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is May 9 and first fall frost is October 15.

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Your Clarion County Garden Planner — Free

A 24-page printable planner built for Clarion County (Zone 6a). 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 Clarion County, PA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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