When to Plant Sunflower in Guadalupe County, TX
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.
Guadalupe County, Texas is in USDA Zone 9a. The average last spring frost is March 7 and the first fall frost is November 21, giving you a growing season of approximately 259 days.
At an elevation of 3,679 feet, Guadalupe County receives approximately 63 inches of rainfall annually with predominantly clay soil. Summer highs average 93°F, providing good warmth for Sunflower during the growing season. Clay soil retains moisture well for Sunflower, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.
Guadalupe County Soil Profile
Soil Type
Clay
Soil pH
6.9-8.2
Drainage
Well Drained
Monthly Watering Guide for Sunflower
Sunflower needs approximately 1 inches of water per week (4.3" 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 | — | 2.1" | 0" | ❄️ Dormant |
| Mar | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 6.5" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 9.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 9.3" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 8" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 7.1" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 6.4" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Nov | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Guadalupe County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sunflower Planting Timeline — Guadalupe County, TX
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 14 | Feb 14 – Feb 28 |
| Transplant Outdoors | February 14 | Feb 14 – Feb 28 |
| Direct Sow | February 14 | Feb 14 – Mar 7 |
| Bloom | May 9 | May 9 – Oct 10 |
Plant 1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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
Low — drought tolerant
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 9a
📆 Growing Season
259 days in Guadalupe County
Growing Tips for Guadalupe County
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
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Guadalupe County, TX?
Guadalupe County is in Zone 9a with an average last frost of March 7. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Guadalupe County, TX?
Guadalupe County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 7 and first fall frost is November 21.
Your Guadalupe County Garden Planner — Free
A 22-page printable planner built for Guadalupe 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.