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When to Plant Sunflower in Litchfield County, CT

Litchfield County, Connecticut Zone 6a May

Your May planting checklist for Litchfield County, Connecticut

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

Avg. last frost April 20
Avg. first frost October 22
Soil temp (4") 62°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Time to transplant sunflower

    Your last frost (April 20) has passed. These warm-season crops can handle outdoor soil now.

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

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Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.

Litchfield County, Connecticut is in USDA Zone 6a. The average last spring frost is April 20 and the first fall frost is October 22, giving you a growing season of approximately 185 days.

At an elevation of 896 feet, Litchfield County receives approximately 49.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Sunflower during the growing season.

Litchfield County, CT (Zone 6a) Moderate season
185 days
Last Spring Frost April 20
185 growing days
First Fall Frost October 22
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Litchfield County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (56 days to spare)
Start indoors: Feb 13 Transplant: Apr 24 🍅 Harvest: Jul 3 – Aug 21
Recommended (50%) ✓ Fits season (52 days to spare)
Start indoors: Feb 23 Transplant: May 4 🍅 Harvest: Jul 13 – Aug 31
Safe Start (90%) ✓ Fits season (40 days to spare)
Start indoors: Mar 21 Transplant: May 30 🍅 Harvest: Aug 8 – Sep 26

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 Litchfield County

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

Soil pH

Your soil pH (5.0–6.6) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
30"
Between Rows

Succession Planting Sunflower

3
successive plantings in your 185-day season

Sow every 8 weeks. Last sowing by Jul 14 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Sunflower

Sunflower needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Sunflower Needs Rainfall You Supplement Action
Jan 3.6" 0" ❄️ Dormant
Feb 3.4" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 2.2" 4.6" 0" ✅ Rainfall sufficient
May 2.2" 4.1" 0" ✅ Rainfall sufficient
Jun 2.2" 4.1" 0" ✅ Rainfall sufficient
Jul 2.2" 4.6" 0" ✅ Rainfall sufficient
Aug 2.2" 4.9" 0" ✅ Rainfall sufficient
Sep 2.2" 4" 0" ✅ Rainfall sufficient
Oct 2.2" 3.9" 0" ✅ Rainfall sufficient
Nov 4.1" 0" ❄️ Dormant
Dec 4.1" 0" ❄️ Dormant

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

Sunflower 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.

Sunflower needs ~1,232 GDD — county provides 2,682 GDD Excellent fit

Sunflower Planting Timeline — Litchfield County, CT

Sunflower Planting Calendar

Activity When Date Range
Start Indoors February 23 Feb 23 – Mar 9
Transplant Outdoors May 4 May 4 – May 18
Direct Sow April 27 Apr 27 – May 18
Harvest July 13 Jul 13 – Aug 31

Plant 1" deep · 18" apart · Rows 30" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

185 days in Litchfield County

Growing Tips for Sunflower in Litchfield County

Direct sow Sunflower outdoors after April 20 in Litchfield County when soil has warmed and frost danger has passed.

Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Litchfield County, CT?

Litchfield County is in Zone 6a with an average last frost of April 20. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Litchfield County, CT?

Litchfield County, Connecticut is in USDA Hardiness Zone 6a. The average last spring frost is April 20 and first fall frost is October 22.

🌱

Your Litchfield County Garden Planner — Free

A 24-page printable planner built for Litchfield 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 Litchfield 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.