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When to Plant Horseradish in Monroe County, MI

Monroe County, Michigan Zone 6b May

May to-do list for Monroe County, Michigan

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

Avg. last frost April 27
Avg. first frost October 17
Soil temp (4") 62°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Move horseradish from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

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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.

Monroe County, Michigan is in USDA Zone 6b. The average last spring frost is April 27 and the first fall frost is October 17, giving you a growing season of approximately 173 days.

At an elevation of 1,202 feet, Monroe County receives approximately 40.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Horseradish during the growing season.

Monroe County, MI (Zone 6b) Moderate season
173 days
Last Spring Frost April 27
173 growing days
First Fall Frost October 17

Monroe County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 8 🍅 Harvest: Sep 11 – Nov 20
Recommended (50%) ✗ May not fit
Transplant: May 11 🍅 Harvest: Sep 14 – Nov 23
Safe Start (90%) ✗ May not fit
Transplant: May 27 🍅 Harvest: Sep 30 – Dec 9

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 Monroe County

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

Soil pH

Your soil pH (5.8–7.2) overlaps with Horseradish's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Horseradish.

Organic Matter

Organic matter is excellent (4.2%) — Horseradish will thrive.

How to Plant Horseradish

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 484 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 1.6" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 4.7" 0" ✅ Rainfall sufficient
Jun 4.3" 5.6" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.5" 0" ✅ Rainfall sufficient
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Monroe 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 2,897 GDD Good fit

Horseradish Planting Timeline — Monroe County, MI

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors May 11 May 11 – May 25
Harvest September 14 Sep 14 – Nov 23

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

Month-by-Month Timeline

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

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 6b

📆 Growing Season

173 days in Monroe County

Growing Tips for Horseradish in Monroe County

Direct sow Horseradish outdoors after April 27 in Monroe County when soil has warmed and frost danger has passed.

Your 173.0-day growing season in Monroe 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 Monroe County, MI?

Monroe County is in Zone 6b with an average last frost of April 27. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Monroe County, MI?

Monroe County, Michigan is in USDA Hardiness Zone 6b. The average last spring frost is April 27 and first fall frost is October 17.

🌱

Your Monroe County Garden Planner — Free

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

Sources & credits

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