Blog

When to Plant Sunflower in McKean County, PA

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.

McKean County, Pennsylvania is in USDA Zone 5a. The average last spring frost is May 18 and the first fall frost is October 4, giving you a growing season of approximately 139 days.

At an elevation of 991 feet, McKean County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Sunflower during the growing season.

McKean County, PA (Zone 5a) Short season
139 days
Last Spring Frost May 18
139 growing days
First Fall Frost October 4

McKean County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Mar 17 Transplant: May 26 🍅 Harvest: Aug 4 – Sep 22
Recommended (50%) ✓ Fits season (6 days to spare)
Start indoors: Mar 23 Transplant: Jun 1 🍅 Harvest: Aug 10 – Sep 28
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: Apr 12 Transplant: Jun 21 🍅 Harvest: Aug 30 – Oct 18

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.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Sunflower needs ~1,169 GDD — county provides 1,911 GDD Excellent fit

Sunflower Planting Timeline โ€” McKean County, PA

Sunflower Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 โ€“ Apr 6
Transplant Outdoors June 1 Jun 1 โ€“ Jun 15
Direct Sow May 25 May 25 โ€“ Jun 15
Harvest August 10 Aug 10 โ€“ Sep 28

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

70โ€“100 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5a

Growing Season

139 days

Growing Tips for McKean County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Sunflower in McKean County, PA?

McKean County is in Zone 5a with an average last frost of May 18. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is McKean County, PA?

McKean County, Pennsylvania is in USDA Hardiness Zone 5a. The average last spring frost is May 18 and first fall frost is October 4.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help McKean County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for McKean County, PA. Local conditions may vary. Last updated: April 2026.