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When to Plant Watermelon in Oxford County, ME

Oxford County, Maine Zone 5a May

May in the garden — Oxford County, Maine

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Oxford County, Maine.

Avg. last frost May 16
Avg. first frost September 29
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Set out watermelon seedlings

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

  2. Scatter watermelon into prepared beds

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Coming up in June — start thinking about
  • Starting indoors: watermelon

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Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound giants.

Oxford County, Maine is in USDA Zone 5a. The average last spring frost is May 16 and the first fall frost is September 29, giving you a growing season of approximately 136 days.

At an elevation of 186 feet, Oxford County receives approximately 39.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Watermelon to ensure they mature before fall.

Oxford County, ME (Zone 5a) Short season
136 days
Last Spring Frost May 16
136 growing days
First Fall Frost September 29
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Oxford County Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (0 days to spare)
Start indoors: Apr 6 Transplant: May 25 🍅 Harvest: Aug 3 – Sep 21
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Apr 11 Transplant: May 30 🍅 Harvest: Aug 8 – Sep 26
Safe Start (90%) ✓ Fits season (6 days to spare)
Start indoors: Apr 25 Transplant: Jun 13 🍅 Harvest: Aug 22 – Oct 10

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 Oxford County

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

Soil pH

Your soil pH (4.9–6.4) is more acidic than Watermelon prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Watermelon.

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Watermelon.

How to Plant Watermelon

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

Succession Planting Watermelon

2
successive plantings in your 136-day season

Sow every 8 weeks. Last sowing by Jun 21 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Watermelon

Watermelon needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Watermelon Needs Rainfall You Supplement Action
Jan 2.7" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.5" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 6.5" 3.8" 2.7" 💧 Light watering
Jun 6.5" 3.6" 2.9" 💧 Light watering
Jul 6.5" 3.7" 2.8" 💧 Light watering
Aug 6.5" 3.6" 2.9" 💧 Light watering
Sep 6.5" 3.3" 3.2" 💧 Light watering
Oct 2.8" 0" ❄️ Dormant
Nov 3.4" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Oxford County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Watermelon 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.

Watermelon needs ~978 GDD — county provides 1,564 GDD Excellent fit

Watermelon Planting Timeline — Oxford County, ME

Watermelon Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors May 30 May 30 – Jun 13
Direct Sow May 23 May 23 – Jun 13
Harvest August 8 Aug 8 – Sep 26

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

136 days in Oxford County

Growing Tips for Watermelon in Oxford County

Direct sow Watermelon outdoors after May 16 in Oxford County when soil has warmed and frost danger has passed.

Common pests for Watermelon in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.

Recommended Watermelon Varieties for Oxford County

Compact, early melons for shorter seasons

Sugar Baby (75d) Blacktail Mountain (70d) Golden Midget (70d)

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Watermelon in Oxford County, ME?

Oxford County is in Zone 5a with an average last frost of May 16. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Oxford County, ME?

Oxford County, Maine is in USDA Hardiness Zone 5a. The average last spring frost is May 16 and first fall frost is September 29.

🌱

Your Oxford County Garden Planner — Free

A 24-page printable planner built for Oxford 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.

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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 Oxford County, ME. 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.