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When to Plant Arugula in Kennebec County, ME

Kennebec County, Maine Zone 5b May

Kennebec County, Maine gardeners: here's your May plan

May is a pivotal month for Kennebec County, Maine gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 10
Avg. first frost October 5
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Move arugula from tray to bed

    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.

A few tasks this May that'll pay off in June
  • Starting indoors: arugula
  • First harvests: arugula

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Arugula is a fast-growing cool-season green with a peppery, nutty flavor. It is excellent in salads and can be harvested as baby greens or mature leaves.

Kennebec County, Maine is in USDA Zone 5b. The average last spring frost is May 10 and the first fall frost is October 5, giving you a growing season of approximately 148 days.

At an elevation of 1,032 feet, Kennebec County receives approximately 42.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Arugula to ensure they mature before fall.

Kennebec County, ME (Zone 5b) Short season
148 days
Last Spring Frost May 10
148 growing days
First Fall Frost October 5
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Kennebec County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (47 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jun 8 – Aug 10
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jun 14 – Aug 16
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Apr 22 Transplant: May 27 🍅 Harvest: Jul 1 – Sep 2

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 Kennebec County

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

Soil pH

Your soil pH (5.1–6.4) is more acidic than Arugula prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Arugula.

How to Plant Arugula

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 Arugula

5
successive plantings in your 148-day season

Sow every 3.4 weeks. Last sowing by Aug 16 to harvest before frost.

For a dedicated fall crop, sow by Jul 27.

Plant Water Budget

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

Monthly Watering Guide for Arugula

Arugula needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Arugula Needs Rainfall You Supplement Action
Jan 3.3" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.5" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 2.6" 3.7" 0" ✅ Rainfall sufficient
Jun 2.6" 3.7" 0" ✅ Rainfall sufficient
Jul 2.6" 3.9" 0" ✅ Rainfall sufficient
Aug 2.6" 4" 0" ✅ Rainfall sufficient
Sep 2.6" 3.9" 0" ✅ Rainfall sufficient
Oct 2.6" 3.8" 0" ✅ Rainfall sufficient
Nov 3.1" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

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

Arugula 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.

Arugula needs ~520 GDD — county provides 1,924 GDD Excellent fit

Arugula Planting Timeline — Kennebec County, ME

Arugula Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow April 26 Apr 26 – May 17
Harvest June 14 Jun 14 – Aug 16
Fall Sowing July 27 Jul 27 – Aug 10

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Direct Sow
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

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5b

📆 Growing Season

148 days in Kennebec County

Growing Tips for Arugula in Kennebec County

Direct sow Arugula outdoors after May 10 in Kennebec County when soil has warmed and frost danger has passed.

Your generous 148.0-day season in Kennebec County allows multiple plantings of Arugula. Sow every 15.0 days for continuous harvest.

Common pests for Arugula in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2-3 weeks for continuous harvest. Provide afternoon shade in warm weather to prevent bolting. Harvest outer leaves first to extend production.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Arugula in Kennebec County, ME?

Kennebec County is in Zone 5b with an average last frost of May 10. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kennebec County, ME?

Kennebec County, Maine is in USDA Hardiness Zone 5b. The average last spring frost is May 10 and first fall frost is October 5.

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Your Kennebec County Garden Planner — Free

A 24-page printable planner built for Kennebec 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.

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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 Kennebec 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.