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When to Plant Sunflower in Jasper County, TX

Jasper County, Texas Zone 9a June

June to-do list for Jasper County, Texas

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Jasper County, Texas.

Avg. last frost March 3
Avg. first frost November 22
Soil temp (4") 84°F
Watering Low
Pest pressure High
Daylight 14 hrs
  1. It's harvest week for sunflower

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

Get ahead of July
  • First harvests: sunflower

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Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.

Jasper County, Texas is in USDA Zone 9a. The average last spring frost is March 3 and the first fall frost is November 22, giving you a growing season of approximately 264 days.

At an elevation of 97 feet, Jasper County receives approximately 71.8 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.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Jasper County, TX (Zone 9a) Long season
264 days
Last Spring Frost March 3
264 growing days
First Fall Frost November 22

Jasper County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Sunflower Planting Risk Windows

Early Start (70% safe) ✓ Fits season (53 days to spare)
Start indoors: Jan 27 Transplant: Jan 27 🌸 Bloom: Apr 21 – Sep 22
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Feb 10 Transplant: Feb 10 🌸 Bloom: May 5 – Oct 6
Safe Start (90%) ✓ Fits season (42 days to spare)
Start indoors: Mar 7 Transplant: Mar 7 🌸 Bloom: May 30 – Oct 31

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 Jasper County

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

Soil pH

Your soil pH (5.3–6.5) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Jasper 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
24"
Between Rows

Succession Planting Sunflower

4
successive plantings in your 264-day season

Sow every 8 weeks. Last sowing by Aug 14 to harvest before frost.

Sunflower Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/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 1.6" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 2.2" 4.2" 0" ✅ Rainfall sufficient
Apr 2.2" 7.3" 0" ✅ Rainfall sufficient
May 2.2" 10.8" 0" ✅ Rainfall sufficient
Jun 2.2" 12.7" 0" ✅ Rainfall sufficient
Jul 2.2" 7.8" 0" ✅ Rainfall sufficient
Aug 2.2" 8.4" 0" ✅ Rainfall sufficient
Sep 2.2" 7.2" 0" ✅ Rainfall sufficient
Oct 2.2" 4.9" 0" ✅ Rainfall sufficient
Nov 2.2" 2.3" 0" ✅ Rainfall sufficient
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Jasper 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 6,006 GDD Excellent fit

Sunflower Planting Timeline — Jasper County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors February 10 Feb 10 – Feb 24
Transplant Outdoors February 10 Feb 10 – Feb 24
Direct Sow February 10 Feb 10 – Mar 3
Bloom May 5 May 5 – Oct 6

Plant 1" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

264 days in Jasper County

Growing Tips for Sunflower in Jasper County

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

Sandy soil in Jasper 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 Jasper 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 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Pole_beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Jasper County, TX?

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

What planting zone is Jasper County, TX?

Jasper County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 3 and first fall frost is November 22.

🌱

Your Jasper County Garden Planner — Free

A 22-page printable planner built for Jasper 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.

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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 Jasper County, TX. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.