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When to Plant Sunflower in Chambers County, TX

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.

Chambers County, Texas is in USDA Zone 9a. The average last spring frost is February 12 and the first fall frost is December 6, giving you a growing season of approximately 297 days.

At an elevation of 1 feet, Chambers County receives approximately 66.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 99ยฐF, so Sunflower may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Sunflower will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.

Chambers County, TX (Zone 9a) Year-round
297 days
Last Spring Frost February 12
297 growing days
First Fall Frost December 6

Chambers County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (182 days to spare)
Start indoors: Dec 13 Transplant: Jan 31 🍅 Harvest: Apr 11 – May 30
Recommended (50%) ✓ Fits season (171 days to spare)
Start indoors: Jan 1 Transplant: Feb 19 🍅 Harvest: Apr 30 – Jun 18
Safe Start (90%) ✓ Fits season (163 days to spare)
Start indoors: Jan 23 Transplant: Mar 13 🍅 Harvest: May 22 – Jul 10

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
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Sunflower needs ~2,061 GDD — county provides 7,226 GDD Excellent fit

Sunflower Planting Timeline โ€” Chambers County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors January 1 Jan 1 โ€“ Jan 15
Transplant Outdoors February 19 Feb 19 โ€“ Mar 5
Direct Sow February 12 Feb 12 โ€“ Mar 5
Harvest April 30 Apr 30 โ€“ Jun 18

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

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Transplant Outdoors Direct Sow
March Transplant Outdoors Direct Sow
April Harvest
May Harvest
June Harvest
July โ€”
August โ€”
September โ€”
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 9a

Growing Season

297 days

Growing Tips for Chambers 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 Chambers County, TX?

Chambers County is in Zone 9a with an average last frost of February 12. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Chambers County, TX?

Chambers County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 12 and first fall frost is December 6.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Chambers County gardeners in Zone 9a organize planting dates, track what's growing, and never miss a planting window.

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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 Chambers County, TX. Local conditions may vary. Last updated: April 2026.