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When to Plant Sunflower in Marion 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.

Marion County, Texas is in USDA Zone 8a. The average last spring frost is March 13 and the first fall frost is November 14, giving you a growing season of approximately 246 days.

At an elevation of 393 feet, Marion County receives approximately 72 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 93ยฐF, providing good warmth for Sunflower during the growing season. 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.

Marion County, TX (Zone 8a) Long season
246 days
Last Spring Frost March 13
246 growing days
First Fall Frost November 14

Marion County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.6-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (111 days to spare)
Start indoors: Jan 15 Transplant: Mar 19 🍅 Harvest: May 28 – Jul 16
Recommended (50%) ✓ Fits season (113 days to spare)
Start indoors: Jan 23 Transplant: Mar 27 🍅 Harvest: Jun 5 – Jul 24
Safe Start (90%) ✓ Fits season (106 days to spare)
Start indoors: Feb 15 Transplant: Apr 19 🍅 Harvest: Jun 28 – Aug 16

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 Marion County

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

Soil pH

Your soil pH (5.6โ€“6.6) overlaps with Sunflower's range (6.0โ€“7.5), though not a perfect match.

Soil Texture

Sandy soil in Marion 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 246-day season

Sow every 8 weeks. Last sowing by Aug 06 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.2″/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 โ€” 2.7" 0" โ„๏ธ Dormant
Mar 2.2" 5" 0" โœ… Rainfall sufficient
Apr 2.2" 8.3" 0" โœ… Rainfall sufficient
May 2.2" 9" 0" โœ… Rainfall sufficient
Jun 2.2" 11.2" 0" โœ… Rainfall sufficient
Jul 2.2" 10.1" 0" โœ… Rainfall sufficient
Aug 2.2" 7.7" 0" โœ… Rainfall sufficient
Sep 2.2" 7.1" 0" โœ… Rainfall sufficient
Oct 2.2" 5" 0" โœ… Rainfall sufficient
Nov 2.2" 2.3" 0" โœ… Rainfall sufficient
Dec โ€” 1.7" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Marโ€“Nov in Marion 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 ~1,679 GDD — county provides 4,858 GDD Excellent fit

Sunflower Planting Timeline โ€” Marion County, TX

Sunflower Planting Calendar

Activity When Date Range
Start Indoors January 23 Jan 23 โ€“ Feb 6
Transplant Outdoors March 27 Mar 27 โ€“ Apr 10
Direct Sow March 20 Mar 20 โ€“ Apr 10
Harvest June 5 Jun 5 โ€“ Jul 24

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

Month-by-Month Timeline

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

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: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 8a

๐Ÿ“† Growing Season

246 days in Marion County

Growing Tips for Sunflower in Marion County

Direct sow Sunflower outdoors after March 13 in Marion County when soil has warmed and frost danger has passed.

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

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 Marion County, TX?

Marion County is in Zone 8a with an average last frost of March 13. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Marion County, TX?

Marion County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 13 and first fall frost is November 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Marion County gardeners in Zone 8a 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 Marion County, TX. Local conditions may vary. Last updated: April 2026.