When to Plant Onion in Blanco County, TX
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Blanco County, Texas is in USDA Zone 8a. The average last spring frost is March 8 and the first fall frost is November 21, giving you a growing season of approximately 258 days.
At an elevation of 4,826 feet, Blanco County receives approximately 61.5 inches of rainfall annually with predominantly clay soil. Summer highs average 90°F, providing good warmth for Onion during the growing season. Clay soil retains moisture well for Onion, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.
Blanco County Soil Profile
Soil Type
Clay
Soil pH
7.1-7.7
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.
Plant Water Budget
Onion Planting Timeline — Blanco County, TX
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 1 | Feb 1 – Feb 15 |
| Transplant Outdoors | March 8 | Mar 8 – Mar 22 |
| Direct Sow | February 22 | Feb 22 – Mar 15 |
| Fall Sowing | September 12 | Sep 12 – Sep 26 |
| Harvest | June 7 | Jun 7 – Jul 26 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | — |
| June | Harvest |
| July | Harvest |
| August | — |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
USDA Zone
Zone 8a
Growing Season
258 days
Growing Tips for Blanco County
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Blanco County, TX?
Blanco County is in Zone 8a with an average last frost of March 8. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Blanco County, TX?
Blanco County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 8 and first fall frost is November 21.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Blanco County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.
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