When to Plant Onion in Dimmit County, TX
May to-do list for Dimmit County, Texas
Here's what deserves your attention in Dimmit County, Texas this month. Everything below is tailored to Zone 9a and timed around your local frost dates.
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Bring in the onion
If you can't use it all right away, check the food-preservation section of your planner.
To set up a strong June, finish these tasks
- First harvests: onion
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.
Dimmit County, Texas is in USDA Zone 9a. The average last spring frost is February 26 and the first fall frost is December 1, giving you a growing season of approximately 278 days.
At an elevation of 2,638 feet, Dimmit County receives approximately 63.2 inches of rainfall annually with predominantly loam soil. Summer highs average 94°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.
Dimmit County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.3
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 Dimmit County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (6.5–7.3) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Dimmit County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Onion.
How to Plant Onion
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Mar | 4.3" | 4" | 0.3" | 💧 Light watering |
| Apr | 4.3" | 6.3" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 9.1" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 11.3" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 8.6" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 8.1" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 5.3" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Nov | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Dec | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
Water needs are for active growing months only (Feb–Dec in Dimmit County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion 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.
Onion Planting Timeline — Dimmit County, TX
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 29 | Jan 29 – Feb 12 |
| Transplant Outdoors | February 26 | Feb 26 – Mar 12 |
| Direct Sow | February 5 | Feb 5 – Feb 26 |
| Harvest | May 28 | May 28 – Jul 16 |
| Fall Sowing | October 6 | Oct 6 – Oct 20 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 9a
📆 Growing Season
278 days in Dimmit County
Growing Tips for Onion in Dimmit County
Direct sow Onion outdoors after February 26 in Dimmit County when soil has warmed and frost danger has passed.
Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
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 Dimmit County, TX?
Dimmit County is in Zone 9a with an average last frost of February 26. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Dimmit County, TX?
Dimmit County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 26 and first fall frost is December 1.
Your Dimmit County Garden Planner — Free
A 24-page printable planner built for Dimmit 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.