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When to Plant Zucchini in Knox County, ME

Knox County, Maine Zone 6a May

May in the garden — Knox County, Maine

Your garden in Knox County, Maine is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 2
Avg. first frost October 12
Soil temp (4") 59°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Plant out zucchini

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

  2. Outdoor sowing time: zucchini

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

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

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Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Knox County, Maine is in USDA Zone 6a. The average last spring frost is May 2 and the first fall frost is October 12, giving you a growing season of approximately 163 days.

At an elevation of 408 feet, Knox County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Zucchini to ensure they mature before fall.

Knox County, ME (Zone 6a) Moderate season
163 days
Last Spring Frost May 2
163 growing days
First Fall Frost October 12

Knox County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Mar 23 Transplant: May 11 🍅 Harvest: Jun 29 – Aug 24
Recommended (50%) ✓ Fits season (44 days to spare)
Start indoors: Mar 28 Transplant: May 16 🍅 Harvest: Jul 4 – Aug 29
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Apr 10 Transplant: May 29 🍅 Harvest: Jul 17 – Sep 11

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 Knox County

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

Soil pH

Your soil pH (5.1–6.7) is more acidic than Zucchini prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Zucchini.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Zucchini.

How to Plant Zucchini

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

Succession Planting Zucchini

4
successive plantings in your 163-day season

Sow every 5.1 weeks. Last sowing by Aug 13 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan 3.1" 0" ❄️ Dormant
Feb 3.1" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 5.2" 3.9" 1.3" 💧 Light watering
Jun 5.2" 4" 1.2" 💧 Light watering
Jul 5.2" 4.1" 1.1" 💧 Light watering
Aug 5.2" 3.8" 1.4" 💧 Light watering
Sep 5.2" 3.4" 1.8" 💧 Light watering
Oct 5.2" 3" 2.2" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

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

Zucchini 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.

Zucchini needs ~643 GDD — county provides 1,996 GDD Excellent fit

Zucchini Planting Timeline — Knox County, ME

Zucchini Planting Calendar

Activity When Date Range
Start Indoors March 28 Mar 28 – Apr 11
Transplant Outdoors May 16 May 16 – May 30
Direct Sow May 9 May 9 – May 30
Harvest July 4 Jul 4 – Aug 29

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Natural rainfall sufficient

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

163 days in Knox County

Growing Tips for Zucchini in Knox County

Direct sow Zucchini outdoors after May 02 in Knox County when soil has warmed and frost danger has passed.

Your generous 163.0-day season in Knox County allows multiple plantings of Zucchini. Sow every 22.0 days for continuous harvest.

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

General growing tips

Direct sow after last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Knox County, ME?

Knox County is in Zone 6a with an average last frost of May 2. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Knox County, ME?

Knox County, Maine is in USDA Hardiness Zone 6a. The average last spring frost is May 2 and first fall frost is October 12.

🌱

Your Knox County Garden Planner — Free

A 24-page printable planner built for Knox County (Zone 6a). 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 Knox 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.