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When to Plant Sunflower in Liberty County, TX

Liberty County, Texas Zone 9a May

Your May game plan for Liberty County, Texas

Each item below is timed to Liberty County, Texas's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost February 14
Avg. first frost December 1
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Bring in the sunflower

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Looking ahead to 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.

Liberty County, Texas is in USDA Zone 9a. The average last spring frost is February 14 and the first fall frost is December 1, giving you a growing season of approximately 290 days.

At an elevation of 141 feet, Liberty County receives approximately 60.7 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 97°F, so Sunflower may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — 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.

Liberty County, TX (Zone 9a) Year-round
290 days
Last Spring Frost February 14
290 growing days
First Fall Frost December 1

Liberty County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.2-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (165 days to spare)
Start indoors: Dec 26 Transplant: Feb 13 🍅 Harvest: Apr 24 – Jun 12
Recommended (50%) ✓ Fits season (164 days to spare)
Start indoors: Jan 3 Transplant: Feb 21 🍅 Harvest: May 2 – Jun 20
Safe Start (90%) ✓ Fits season (161 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 Liberty County

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

Soil pH

Your soil pH (5.2–6.2) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Liberty County warms quickly in spring but drains fast. Sunflower will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is low (1.7%). Add 2-3 inches of compost before planting Sunflower.

How to Plant Sunflower

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

Succession Planting Sunflower

4
successive plantings in your 290-day season

Sow every 8 weeks. Last sowing by Aug 23 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 1.2" 0" ❄️ Dormant
Feb 2.2" 2.2" 0" ✅ Rainfall sufficient
Mar 2.2" 3.8" 0" ✅ Rainfall sufficient
Apr 2.2" 6.5" 0" ✅ Rainfall sufficient
May 2.2" 8.6" 0" ✅ Rainfall sufficient
Jun 2.2" 10.6" 0" ✅ Rainfall sufficient
Jul 2.2" 7.4" 0" ✅ Rainfall sufficient
Aug 2.2" 7.6" 0" ✅ Rainfall sufficient
Sep 2.2" 5.8" 0" ✅ Rainfall sufficient
Oct 2.2" 3.6" 0" ✅ Rainfall sufficient
Nov 2.2" 1.7" 0.5" 💧 Light watering
Dec 2.2" 1.6" 0.6" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Liberty 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 ~1,934 GDD — county provides 6,620 GDD Excellent fit

Sunflower Planting Timeline — Liberty County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors January 3 Jan 3 – Jan 17
Transplant Outdoors February 21 Feb 21 – Mar 7
Direct Sow February 14 Feb 14 – Mar 7
Harvest May 2 May 2 – Jun 20

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

Month-by-Month Timeline

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

📆 Growing Season

290 days in Liberty County

Growing Tips for Sunflower in Liberty County

Direct sow Sunflower outdoors after February 14 in Liberty County when soil has warmed and frost danger has passed.

Sandy soil in Liberty County dries quickly — mulch Sunflower with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 97°F in Liberty 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 Liberty County, TX?

Liberty County is in Zone 9a with an average last frost of February 14. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Liberty County, TX?

Liberty County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 14 and first fall frost is December 1.

🌱

Your Liberty County Garden Planner — Free

A 24-page printable planner built for Liberty County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Liberty 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.