When to Plant Yarrow in Somerset County, ME
May in Somerset County, Maine — your action list
Welcome to May in Zone 5a. These are the moves that will have the biggest impact on your growing season.
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Set out yarrow seedlings
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.
Yarrow is a drought-tolerant perennial herb with feathery foliage and flat-topped flower clusters in white, yellow, pink, or red. It attracts beneficial insects and is used in herbal medicine.
Somerset County, Maine is in USDA Zone 5a. The average last spring frost is May 22 and the first fall frost is September 26, giving you a growing season of approximately 127 days.
At an elevation of 356 feet, Somerset County receives approximately 48.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Yarrow to ensure they mature before fall.
Somerset County Soil Profile
Soil Type
Silt Loam
Soil pH
4.8-6.4
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 Somerset County
How your county's soil matches Yarrow's growing requirements.
Soil pH
Your soil pH (4.8–6.4) overlaps with Yarrow's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Somerset County is excellent for Yarrow — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Yarrow prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.
Organic Matter
Organic matter is moderate (3.3%). Annual compost additions will help Yarrow.
How to Plant Yarrow
Plant Water Budget
Monthly Watering Guide for Yarrow
Yarrow needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Yarrow Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 3.2" | 0" | ❄️ Dormant |
| Mar | — | 4.5" | 0" | ❄️ Dormant |
| Apr | — | 4.6" | 0" | ❄️ Dormant |
| May | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Oct | — | 4.2" | 0" | ❄️ Dormant |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Somerset County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Yarrow 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.
Yarrow Planting Timeline — Somerset County, ME
Yarrow Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 29 | May 29 – Jun 12 |
| Harvest | August 28 | Aug 28 – Nov 13 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
127 days in Somerset County
Growing Tips for Yarrow in Somerset County
Direct sow Yarrow outdoors after May 22 in Somerset County when soil has warmed and frost danger has passed.
Your 127.0-day growing season in Somerset County is tight for Yarrow (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Yarrow in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow or start from divisions. Yarrow thrives in poor soil and is very drought-tolerant. Deadhead to encourage reblooming. Divide clumps every 3 years.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Yarrow in Other Locations
Frequently Asked Questions
When should I plant Yarrow in Somerset County, ME?
Somerset County is in Zone 5a with an average last frost of May 22. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.
What planting zone is Somerset County, ME?
Somerset County, Maine is in USDA Hardiness Zone 5a. The average last spring frost is May 22 and first fall frost is September 26.
Your Somerset County Garden Planner — Free
A 24-page printable planner built for Somerset County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.