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When to Plant Sunflower in Brooks 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.

Brooks County, Texas is in USDA Zone 9a. The average last spring frost is February 10 and the first fall frost is December 13, giving you a growing season of approximately 306 days.

At an elevation of 2,752 feet, Brooks County receives approximately 64.5 inches of rainfall annually with predominantly loam soil. Summer highs average 104ยฐF, so Sunflower may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.

Brooks County, TX (Zone 9a) Year-round
306 days
Last Spring Frost February 10
306 growing days
First Fall Frost December 13

Brooks County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (193 days to spare)
Start indoors: Dec 8 Transplant: Jan 26 🍅 Harvest: Apr 6 – May 25
Recommended (50%) ✓ Fits season (180 days to spare)
Start indoors: Dec 30 Transplant: Feb 17 🍅 Harvest: Apr 28 – Jun 16
Safe Start (90%) ✓ Fits season (166 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.

Soil Compatibility in Brooks County

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

Soil pH

Your soil pH (6.7โ€“7.2) is within Sunflower's preferred range (6.0โ€“7.5).

Soil Texture

The loam soil in Brooks County is excellent for Sunflower โ€” good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Sunflower.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Sunflower.

How to Plant Sunflower

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

Succession Planting Sunflower

5
successive plantings in your 306-day season

Sow every 8 weeks. Last sowing by Sep 04 to harvest before frost.

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

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 โ€” 1.9" 0" โ„๏ธ Dormant
Feb 2.2" 2.5" 0" โœ… Rainfall sufficient
Mar 2.2" 3.6" 0" โœ… Rainfall sufficient
Apr 2.2" 6.1" 0" โœ… Rainfall sufficient
May 2.2" 10.3" 0" โœ… Rainfall sufficient
Jun 2.2" 10.5" 0" โœ… Rainfall sufficient
Jul 2.2" 7.3" 0" โœ… Rainfall sufficient
Aug 2.2" 7.2" 0" โœ… Rainfall sufficient
Sep 2.2" 6" 0" โœ… Rainfall sufficient
Oct 2.2" 4.8" 0" โœ… Rainfall sufficient
Nov 2.2" 2.3" 0" โœ… Rainfall sufficient
Dec 2.2" 1.8" 0.4" ๐Ÿ’ง Light watering

Water needs are for active growing months only (Febโ€“Dec in Brooks County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 ~2,380 GDD — county provides 8,596 GDD Excellent fit

Sunflower Planting Timeline โ€” Brooks County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors December 30 Dec 30 โ€“ Jan 13
Transplant Outdoors February 17 Feb 17 โ€“ Mar 3
Direct Sow February 10 Feb 10 โ€“ Mar 3
Harvest April 28 Apr 28 โ€“ Jun 16

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 Start Indoors

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.5"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

70โ€“100 days

๐Ÿงช Soil pH

Needs 6โ€“7.5 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 9a

๐Ÿ“† Growing Season

306 days in Brooks County

Growing Tips for Sunflower in Brooks County

Direct sow Sunflower outdoors after February 10 in Brooks County when soil has warmed and frost danger has passed.

With summer highs reaching 104ยฐF in Brooks County, provide afternoon shade for Sunflower and water deeply in the morning.

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 Brooks County, TX?

Brooks County is in Zone 9a with an average last frost of February 10. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Brooks County, TX?

Brooks County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 10 and first fall frost is December 13.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Brooks County gardeners in Zone 9a 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 Brooks County, TX. Local conditions may vary. Last updated: April 2026.