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When to Plant Rutabaga in Penobscot County, ME

Penobscot County, Maine Zone 5a May

Your May planting checklist for Penobscot County, Maine

Welcome to May in Zone 5a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 10
Avg. first frost October 2
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs

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Rutabagas are a cross between turnips and cabbage, producing large yellow-fleshed roots with a sweet, mild flavor. They are excellent mashed, roasted, or in stews.

Penobscot County, Maine is in USDA Zone 5a. The average last spring frost is May 10 and the first fall frost is October 2, giving you a growing season of approximately 145 days.

At an elevation of 842 feet, Penobscot County receives approximately 38.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Rutabaga to ensure they mature before fall.

Penobscot County, ME (Zone 5a) Short season
145 days
Last Spring Frost May 10
145 growing days
First Fall Frost October 2
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Penobscot County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Transplant: May 7 🍅 Harvest: Jul 30 – Sep 3
Recommended (50%) ✓ Fits season (26 days to spare)
Transplant: May 10 🍅 Harvest: Aug 2 – Sep 6
Safe Start (90%) ✓ Fits season (29 days to spare)
Transplant: May 25 🍅 Harvest: Aug 17 – Sep 21

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 Penobscot County

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

Soil pH

Your soil pH (4.8–6.7) is more acidic than Rutabaga prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). Annual compost additions will help Rutabaga.

How to Plant Rutabaga

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Rutabaga

2
successive plantings in your 145-day season

Sow every 9.1 weeks. Last sowing by Jun 24 to harvest before frost.

For a dedicated fall crop, sow by Jul 24.

Plant Water Budget

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

Monthly Watering Guide for Rutabaga

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

Month Rutabaga Needs Rainfall You Supplement Action
Jan 2.4" 0" ❄️ Dormant
Feb 2.3" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 3" 3.9" 0" ✅ Rainfall sufficient
Jun 3" 3.9" 0" ✅ Rainfall sufficient
Jul 3" 3.5" 0" ✅ Rainfall sufficient
Aug 3" 3.2" 0" ✅ Rainfall sufficient
Sep 3" 3.7" 0" ✅ Rainfall sufficient
Oct 3" 3.6" 0" ✅ Rainfall sufficient
Nov 3.2" 0" ❄️ Dormant
Dec 2.6" 0" ❄️ Dormant

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

Rutabaga 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.

Rutabaga needs ~1,102 GDD — county provides 1,776 GDD Excellent fit

Rutabaga Planting Timeline — Penobscot County, ME

Rutabaga Planting Calendar

Activity When Date Range
Direct Sow April 26 Apr 26 – May 17
Harvest July 19 Jul 19 – Aug 23
Fall Sowing July 24 Jul 24 – Aug 7

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

145 days in Penobscot County

Growing Tips for Rutabaga in Penobscot County

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

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

General growing tips

Direct sow in early summer for fall harvest. Thin seedlings to 6-8 inches apart. Flavor improves significantly after a few light frosts.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rutabaga in Penobscot County, ME?

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

What planting zone is Penobscot County, ME?

Penobscot County, Maine is in USDA Hardiness Zone 5a. The average last spring frost is May 10 and first fall frost is October 2.

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Your Penobscot County Garden Planner — Free

A 24-page printable planner built for Penobscot 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 Penobscot 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.