When to Plant Onion in Callahan 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.
Callahan County, Texas is in USDA Zone 8a. The average last spring frost is March 21 and the first fall frost is November 16, giving you a growing season of approximately 240 days.
At an elevation of 4,241 feet, Callahan County receives approximately 59.1 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Onion during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.
Callahan County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.4
Drainage
Well Drained
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | 4.3" | 3.3" | 1" | 💧 Light watering |
| Apr | 4.3" | 5.9" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 7.8" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 11" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 8.5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 6.1" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 5.7" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Nov | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Callahan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion Planting Timeline — Callahan County, TX
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 14 | Feb 14 – Feb 28 |
| Transplant Outdoors | March 21 | Mar 21 – Apr 4 |
| Direct Sow | March 7 | Mar 7 – Mar 28 |
| Harvest | June 20 | Jun 20 – Aug 8 |
| Fall Sowing | September 7 | Sep 7 – Sep 21 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Transplant Outdoors Direct Sow |
| April | Transplant Outdoors |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| 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
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 8a
📆 Growing Season
240 days in Callahan County
Growing Tips for Callahan 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
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Callahan County, TX?
Callahan County is in Zone 8a with an average last frost of March 21. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Callahan County, TX?
Callahan County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 21 and first fall frost is November 16.
Your Callahan County Garden Planner — Free
A 22-page printable planner built for Callahan County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.