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When to plant Sunflower in Hampden County, MA

For Hampden County, gardeners: plant Sunflower May 7 through May 28 once soil reads 50°F.

When to Plant Sunflower in Hampden County, MA

Hampden County, Massachusetts Zone 6a June

Your June gardening checklist

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 30
Avg. first frost October 17
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 15.1 hrs
To set up a strong July, finish these tasks
  • First harvests: sunflower

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Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.

Hampden County, Massachusetts is in USDA Zone 6a. The average last spring frost is April 30 and the first fall frost is October 17, giving you a growing season of approximately 170 days.

At an elevation of 474 feet, Hampden County receives approximately 47.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Sunflower during the growing season.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Hampden County, MA (Zone 6a) Moderate season
170 days
Last Spring Frost April 30
170 growing days
First Fall Frost October 17

Hampden County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.4

Drainage

Well Drained

Sunflower Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 4 Transplant: May 2 🌸 Bloom: Jul 25 – Oct 17
Recommended (50%) ✗ May not fit
Start indoors: Apr 9 Transplant: May 7 🌸 Bloom: Jul 30 – Oct 22
Safe Start (90%) ✗ May not fit
Start indoors: Apr 26 Transplant: May 24 🌸 Bloom: Aug 16 – Nov 8

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 Hampden County

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

Soil pH

Your soil pH (5.1–6.4) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Sunflower.

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Sunflower

2
successive plantings in your 170-day season

Sow every 8 weeks. Last sowing by Jul 09 to harvest before frost.

Sunflower Water Budget

Plant needs
0.5″/week
Rainfall provides
1.2″/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 3.5" 0" ❄️ Dormant
Mar 4.3" 0" ❄️ Dormant
Apr 2.2" 3.4" 0" ✅ Rainfall sufficient
May 2.2" 4.7" 0" ✅ Rainfall sufficient
Jun 2.2" 4.6" 0" ✅ Rainfall sufficient
Jul 2.2" 4.8" 0" ✅ Rainfall sufficient
Aug 2.2" 4" 0" ✅ Rainfall sufficient
Sep 2.2" 3.4" 0" ✅ Rainfall sufficient
Oct 2.2" 4.3" 0" ✅ Rainfall sufficient
Nov 3.8" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Hampden 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 ~1,360 GDD — county provides 2,720 GDD Excellent fit

Sunflower Planting Timeline — Hampden County, MA

Sunflower Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 7 May 7 – May 21
Direct Sow May 7 May 7 – May 28
Bloom July 30 Jul 30 – Oct 22

Plant 1" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

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

170 days in Hampden County

Growing Tips for Sunflower in Hampden County

Direct sow Sunflower outdoors after April 30 in Hampden 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 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Pole_beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Hampden County, MA?

Hampden County is in Zone 6a with an average last frost of April 30. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hampden County, MA?

Hampden County, Massachusetts is in USDA Hardiness Zone 6a. The average last spring frost is April 30 and first fall frost is October 17.

When should I plant Sunflower in Hampden County, MA?

In Hampden County, MA, plant Sunflower after the last frost (around April 30) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Hampden County, MA for Sunflower?

Hampden County sits in USDA Zone 6a. Sunflower grows reliably in zones 2a through 11b, so it's a good fit here.

Can Sunflower grow in Hampden County's climate?

Yes — Sunflower grows well in Hampden County's temperate climate. Hampden County averages a 170-day frost-free season, with last frost around April 30 and first frost around October 17.

🌱

Your Hampden County Garden Planner — Free

A 22-page printable planner built for Hampden 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 Hampden County, MA. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.