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When to Plant Sunflower in Zapata County, TX

Zapata County, Texas Zone 9b May

Your May game plan for Zapata County, Texas

We've pulled the most time-sensitive tasks for Zapata County, Texas this May and put them front and centre. Tackle them in order.

Avg. last frost February 3
Avg. first frost December 14
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 13.3 hrs
  1. Collect sunflower at their peak

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

A few tasks this May that'll pay off in June
  • First harvests: 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.

Zapata County, Texas is in USDA Zone 9b. The average last spring frost is February 3 and the first fall frost is December 14, giving you a growing season of approximately 314 days.

At an elevation of 3,340 feet, Zapata County receives approximately 60.6 inches of rainfall annually with predominantly loam soil. Summer highs average 103°F, 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.

Zapata County, TX (Zone 9b) Year-round
314 days
Last Spring Frost February 3
314 growing days
First Fall Frost December 14
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Zapata County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (197 days to spare)
Start indoors: Dec 6 Transplant: Jan 24 🍅 Harvest: Apr 4 – May 23
Recommended (50%) ✓ Fits season (188 days to spare)
Start indoors: Dec 23 Transplant: Feb 10 🍅 Harvest: Apr 21 – Jun 9
Safe Start (90%) ✓ Fits season (174 days to spare)
Start indoors: Jan 16 Transplant: Mar 6 🍅 Harvest: May 15 – Jul 3

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 Zapata County

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

Soil pH

Your soil pH (6.2–7.6) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). 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 314-day season

Sow every 8 weeks. Last sowing by Sep 05 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/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 1.3" 0" ❄️ Dormant
Feb 2.2" 2.3" 0" ✅ Rainfall sufficient
Mar 2.2" 4.1" 0" ✅ Rainfall sufficient
Apr 2.2" 6.3" 0" ✅ Rainfall sufficient
May 2.2" 7.6" 0" ✅ Rainfall sufficient
Jun 2.2" 10.1" 0" ✅ Rainfall sufficient
Jul 2.2" 8.6" 0" ✅ Rainfall sufficient
Aug 2.2" 7.4" 0" ✅ Rainfall sufficient
Sep 2.2" 6.1" 0" ✅ Rainfall sufficient
Oct 2.2" 3.3" 0" ✅ Rainfall sufficient
Nov 2.2" 2" 0.2" 💧 Light watering
Dec 2.2" 1.3" 0.9" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Zapata 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 ~2,316 GDD — county provides 8,583 GDD Excellent fit

Sunflower Planting Timeline — Zapata County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors December 23 Dec 23 – Jan 6
Transplant Outdoors February 10 Feb 10 – Feb 24
Direct Sow February 3 Feb 3 – Feb 24
Harvest April 21 Apr 21 – Jun 9

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 9b

📆 Growing Season

314 days in Zapata County

Growing Tips for Sunflower in Zapata County

Direct sow Sunflower outdoors after February 03 in Zapata County when soil has warmed and frost danger has passed.

With summer highs reaching 103°F in Zapata 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 Zapata County, TX?

Zapata County is in Zone 9b with an average last frost of February 3. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Zapata County, TX?

Zapata County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 3 and first fall frost is December 14.

🌱

Your Zapata County Garden Planner — Free

A 24-page printable planner built for Zapata County (Zone 9b). 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 Zapata County, TX. 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.