When to Plant Sunflower in San Jacinto 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.
San Jacinto County, Texas is in USDA Zone 8b. The average last spring frost is February 18 and the first fall frost is December 1, giving you a growing season of approximately 286 days.
At an elevation of 6 feet, San Jacinto County receives approximately 71.3 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 94°F, providing good warmth for Sunflower during the growing season. 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.
San Jacinto County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.3-6.7
Drainage
Well Drained
Plant Planting Risk Windows
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 San Jacinto County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (5.3–6.7) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
Sandy soil in San Jacinto 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 moderate (2.2%). Annual compost additions will help Sunflower.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Aug 23 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | 2.2" | 2.5" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 8.5" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 9.5" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 11.4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 9.2" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 8" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 6.7" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 5.2" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Dec | 2.2" | 1.9" | 0.3" | 💧 Light watering |
Water needs are for active growing months only (Feb–Dec in San Jacinto 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 Planting Timeline — San Jacinto County, TX
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 31 | Dec 31 – Jan 14 |
| Transplant Outdoors | March 4 | Mar 4 – Mar 18 |
| Direct Sow | February 25 | Feb 25 – Mar 18 |
| Harvest | May 13 | May 13 – Jul 1 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | Start Indoors |
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 8b
📆 Growing Season
286 days in San Jacinto County
Growing Tips for Sunflower in San Jacinto County
Direct sow Sunflower outdoors after February 18 in San Jacinto County when soil has warmed and frost danger has passed.
Sandy soil in San Jacinto County dries quickly — 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
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in San Jacinto County, TX?
San Jacinto County is in Zone 8b with an average last frost of February 18. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Jacinto County, TX?
San Jacinto County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is February 18 and first fall frost is December 1.
Plan Your Garden with Confidence
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