When to Plant Onion in Decatur County, TN
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.
Decatur County, Tennessee is in USDA Zone 7a. The average last spring frost is April 5 and the first fall frost is October 27, giving you a growing season of approximately 205 days.
At an elevation of 1,168 feet, Decatur County receives approximately 55 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°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.
Decatur County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.5
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 — Decatur County, TN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 1 | Mar 1 – Mar 15 |
| Transplant Outdoors | April 5 | Apr 5 – Apr 19 |
| Direct Sow | March 22 | Mar 22 – Apr 12 |
| Fall Sowing | August 18 | Aug 18 – Sep 1 |
| Harvest | July 5 | Jul 5 – Aug 23 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing 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
6 – 7
USDA Zone
Zone 7a
Growing Season
205 days
Growing Tips for Decatur 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 Decatur County, TN?
Decatur County is in Zone 7a with an average last frost of April 5. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Decatur County, TN?
Decatur County, Tennessee is in USDA Hardiness Zone 7a. The average last spring frost is April 5 and first fall frost is October 27.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Decatur County gardeners in Zone 7a organize planting dates, track what's growing, and never miss a planting window.
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