When to Plant Horseradish in Washington County, ME
Your May game plan for Washington County, Maine
May is a pivotal month for Washington County, Maine gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Transplant horseradish outside
Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.
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.
Washington County, Maine is in USDA Zone 5b. The average last spring frost is May 9 and the first fall frost is October 7, giving you a growing season of approximately 151 days.
At an elevation of 1,184 feet, Washington County receives approximately 43.9 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.
Washington County Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.5
Drainage
Well Drained
Plant Planting Risk Windows
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 Washington County
How your county's soil matches Horseradish's growing requirements.
Soil pH
Your soil pH (5.0–6.5) is more acidic than Horseradish prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Washington County is excellent for Horseradish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.7%). Annual compost additions will help Horseradish.
How to Plant Horseradish
Plant Water Budget
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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | — | 3" | 0" | ❄️ Dormant |
| Mar | — | 4.1" | 0" | ❄️ Dormant |
| Apr | — | 3.5" | 0" | ❄️ Dormant |
| May | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Jun | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Sep | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Oct | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Nov | — | 3.4" | 0" | ❄️ Dormant |
| Dec | — | 3.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Washington 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 Planting Timeline — Washington County, ME
Horseradish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 23 | May 23 – Jun 6 |
| Harvest | September 26 | Sep 26 – Nov 7 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | — |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
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 5b
📆 Growing Season
151 days in Washington County
Growing Tips for Horseradish in Washington County
Direct sow Horseradish outdoors after May 09 in Washington County when soil has warmed and frost danger has passed.
Your 151.0-day growing season in Washington 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 →
Horseradish in Other Locations
Frequently Asked Questions
When should I plant Horseradish in Washington County, ME?
Washington County is in Zone 5b 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 Washington County, ME?
Washington County, Maine is in USDA Hardiness Zone 5b. The average last spring frost is May 9 and first fall frost is October 7.
Your Washington County Garden Planner — Free
A 24-page printable planner built for Washington County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.