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When to Plant Spinach in Oxford County, ME

Oxford County, Maine Zone 5a May

Your May planting checklist for Oxford County, Maine

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

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. Move spinach from tray to bed

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

  2. Put spinach seeds straight in the ground

    Your soil is 56°F — warm enough for these to germinate without babying.

June will be here before you know it — start on
  • Starting indoors: spinach
  • First harvests: spinach

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Spinach is a nutrient-packed cool-season green that grows quickly in spring and fall. It is rich in iron, vitamins, and antioxidants and excellent raw or cooked.

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 Spinach 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 (35 days to spare)
Start indoors: Apr 6 Transplant: May 11 🍅 Harvest: Jun 15 – Aug 17
Recommended (50%) ✓ Fits season (38 days to spare)
Start indoors: Apr 11 Transplant: May 16 🍅 Harvest: Jun 20 – Aug 22
Safe Start (90%) ✓ Fits season (41 days to spare)
Start indoors: Apr 25 Transplant: May 30 🍅 Harvest: Jul 4 – Sep 5

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 Spinach's growing requirements.

Soil pH

Your soil pH (4.9–6.4) is more acidic than Spinach prefers (6.5–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Spinach.

Organic Matter

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

How to Plant Spinach

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

4
successive plantings in your 136-day season

Sow every 4 weeks. Last sowing by Aug 10 to harvest before frost.

For a dedicated fall crop, sow by Jul 21.

Plant Water Budget

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

Monthly Watering Guide for Spinach

Spinach needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Spinach 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 3" 3.8" 0" ✅ Rainfall sufficient
Jun 3" 3.6" 0" ✅ Rainfall sufficient
Jul 3" 3.7" 0" ✅ Rainfall sufficient
Aug 3" 3.6" 0" ✅ Rainfall sufficient
Sep 3" 3.3" 0" ✅ Rainfall sufficient
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.

Spinach 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.

Spinach needs ~489 GDD — county provides 1,564 GDD Excellent fit

Spinach Planting Timeline — Oxford County, ME

Spinach Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors May 16 May 16 – May 30
Direct Sow May 2 May 2 – May 23
Harvest June 20 Jun 20 – Aug 22
Fall Sowing July 21 Jul 21 – Aug 4

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

136 days in Oxford County

Growing Tips for Spinach in Oxford County

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

Your generous 136.0-day season in Oxford County allows multiple plantings of Spinach. Sow every 17.0 days for continuous harvest.

General growing tips

Direct sow as soon as soil can be worked in spring. Plant in partial shade for summer crops to delay bolting. Succession plant every 2 weeks for continuous harvest.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Spinach Seeds
Life Cycle Annual
Pollination Wind Pollinated
How to Collect Let plants bolt. Harvest seed stalks when seeds turn tan.
Storage Store airtight; viable 5 years at 35°F, under 45% humidity.

Wind pollinated — isolate 1/2 mile for purity. Easy to let bolt in heat.

Frequently Asked Questions

When should I plant Spinach in Oxford County, ME?

Oxford County is in Zone 5a with an average last frost of May 16. Plan your Spinach 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.