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When to Plant Squash (Summer) in New Haven County, CT

New Haven County, Connecticut Zone 6b May

Your May planting checklist for New Haven County, Connecticut

Here's what deserves your attention in New Haven County, Connecticut this month. Everything below is tailored to Zone 6b and timed around your local frost dates.

Avg. last frost April 23
Avg. first frost October 19
Soil temp (4") 63°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Plant out squash (summer)

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Start squash (summer) under lights

    Your window is short. These crops want several weeks of indoor growth before they go outside.

June prep starts now
  • First harvests: squash (summer)

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Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

New Haven County, Connecticut is in USDA Zone 6b. The average last spring frost is April 23 and the first fall frost is October 19, giving you a growing season of approximately 179 days.

At an elevation of 509 feet, New Haven County receives approximately 49.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Squash (Summer) during the growing season.

New Haven County, CT (Zone 6b) Moderate season
179 days
Last Spring Frost April 23
179 growing days
First Fall Frost October 19
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New Haven County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 10 Transplant: Apr 28 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Mar 19 Transplant: May 7 🍅 Harvest: Jun 25 – Aug 27
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Apr 11 Transplant: May 30 🍅 Harvest: Jul 18 – Sep 19

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 New Haven County

How your county's soil matches Squash (Summer)'s growing requirements.

Soil pH

Your soil pH (5.0–6.5) is more acidic than Squash (Summer) prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in New Haven County is excellent for Squash (Summer) — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.1%). Annual compost additions will help Squash (Summer).

How to Plant Squash (Summer)

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

Succession Planting Squash (Summer)

4
successive plantings in your 179-day season

Sow every 5.1 weeks. Last sowing by Aug 15 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Squash (Summer)

Squash (Summer) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Squash (Summer) Needs Rainfall You Supplement Action
Jan 3.5" 0" ❄️ Dormant
Feb 3.4" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 4.3" 4.2" 0.1" 💧 Light watering
May 4.3" 4.5" 0" ✅ Rainfall sufficient
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 5.2" 0" ✅ Rainfall sufficient
Aug 4.3" 4.4" 0" ✅ Rainfall sufficient
Sep 4.3" 3.6" 0.7" 💧 Light watering
Oct 4.3" 4.2" 0.1" 💧 Light watering
Nov 4.2" 0" ❄️ Dormant
Dec 4" 0" ❄️ Dormant

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

Squash (Summer) 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.

Squash (Summer) needs ~921 GDD — county provides 2,998 GDD Excellent fit

Squash (Summer) Planting Timeline — New Haven County, CT

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors May 7 May 7 – May 21
Direct Sow April 30 Apr 30 – May 21
Harvest June 25 Jun 25 – Aug 27

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6b

📆 Growing Season

179 days in New Haven County

Growing Tips for Squash (Summer) in New Haven County

Direct sow Squash (Summer) outdoors after April 23 in New Haven County when soil has warmed and frost danger has passed.

Your generous 179.0-day season in New Haven County allows multiple plantings of Squash (Summer). Sow every 22.0 days for continuous harvest.

Common pests for Squash (Summer) 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 on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Squash (Summer) in New Haven County, CT?

New Haven County is in Zone 6b with an average last frost of April 23. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.

What planting zone is New Haven County, CT?

New Haven County, Connecticut is in USDA Hardiness Zone 6b. The average last spring frost is April 23 and first fall frost is October 19.

🌱

Your New Haven County Garden Planner — Free

A 24-page printable planner built for New Haven County (Zone 6b). 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 New Haven County, CT. 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.