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When to Plant Horseradish in Mille Lacs County, MN

Mille Lacs County, Minnesota Zone 4a May

What to do in May

Each item below is timed to Mille Lacs County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 1
Avg. first frost October 6
Soil temp (4") 53°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Move horseradish from tray to bed

    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.

Mille Lacs County, Minnesota is in USDA Zone 4a. The average last spring frost is May 1 and the first fall frost is October 6, giving you a growing season of approximately 158 days.

At an elevation of 874 feet, Mille Lacs County receives approximately 31.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Horseradish to ensure they mature before fall.

Mille Lacs County, MN (Zone 4a) Moderate season
158 days
Last Spring Frost May 1
158 growing days
First Fall Frost October 6
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Mille Lacs County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 9 🍅 Harvest: Sep 12 – Oct 3
Recommended (50%) ✗ May not fit
Transplant: May 15 🍅 Harvest: Sep 18 – Oct 9
Safe Start (90%) ✗ May not fit
Transplant: Jun 1 🍅 Harvest: Oct 5 – Oct 26

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 Mille Lacs County

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

Soil pH

Your soil pH (5.9–7.3) overlaps with Horseradish's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — 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
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 236 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 1.3" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 3.9" 0.4" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Mille Lacs 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 ~1,500 GDD — county provides 1,580 GDD Good fit

Horseradish Planting Timeline — Mille Lacs County, MN

Horseradish Planting Calendar

Activity When Date Range
Transplant Outdoors May 15 May 15 – May 29
Harvest September 18 Sep 18 – Oct 9

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
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

158 days in Mille Lacs County

Growing Tips for Horseradish in Mille Lacs County

Direct sow Horseradish outdoors after May 01 in Mille Lacs County when soil has warmed and frost danger has passed.

Your 158.0-day growing season in Mille Lacs 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 Mille Lacs County, MN?

Mille Lacs County is in Zone 4a with an average last frost of May 1. Plan your Horseradish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mille Lacs County, MN?

Mille Lacs County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 1 and first fall frost is October 6.

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Your Mille Lacs County Garden Planner — Free

A 24-page printable planner built for Mille Lacs County (Zone 4a). 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 Mille Lacs County, MN. 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.