When to Plant Sweet Potatoes in Somerset County, ME
May in the garden — Somerset County, Maine
May is a pivotal month for Somerset County, Maine gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Plant sweet potatoes from seed, right in the garden
Your soil is 54°F — warm enough for these to germinate without babying.
A few tasks this May that'll pay off in June
- Transplants going out: sweet potatoes
Sweet potatoes are a warm-season root crop that produces nutritious, sweet tubers in orange, white, and purple varieties. They need a long, hot growing season.
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 Sweet Potatoes 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 Sweet Potatoes's growing requirements.
Soil pH
Your soil pH (4.8–6.4) overlaps with Sweet Potatoes's range (5.5–6.5), though not a perfect match.
Soil Texture
The silt loam soil in Somerset County is excellent for Sweet Potatoes — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Sweet Potatoes.
Organic Matter
Organic matter is moderate (3.3%). Annual compost additions will help Sweet Potatoes.
How to Plant Sweet Potatoes
Plant Water Budget
Monthly Watering Guide for Sweet Potatoes
Sweet Potatoes needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sweet Potatoes 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 | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Jun | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4" | 0.3" | 💧 Light watering |
| Aug | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 4" | 0.3" | 💧 Light watering |
| 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.
Sweet Potatoes 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.
Sweet Potatoes Planting Timeline — Somerset County, ME
Sweet Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 27 | Mar 27 – Apr 10 |
| Transplant Outdoors | June 5 | Jun 5 – Jun 19 |
| Direct Sow | May 29 | May 29 – Jun 19 |
| Harvest | September 4 | Sep 4 – Oct 23 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | — |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
127 days in Somerset County
Growing Tips for Sweet Potatoes in Somerset County
Direct sow Sweet Potatoes 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 Sweet Potatoes (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Plant slips (rooted sprouts) after soil is thoroughly warm. Build raised mounds for better root development. Cure harvested roots at 80-85F for 10 days to develop sweetness.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Potatoes in Other Locations
Frequently Asked Questions
When should I plant Sweet Potatoes in Somerset County, ME?
Somerset County is in Zone 5a with an average last frost of May 22. Plan your Sweet Potatoes 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.