When to Plant Onion in Putnam 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.
Putnam County, Tennessee is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 26, giving you a growing season of approximately 199 days.
At an elevation of 1,813 feet, Putnam County receives approximately 51.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°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.
Putnam County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.7
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 | — | 4.1" | 0" | ❄️ Dormant |
| Feb | — | 3.5" | 0" | ❄️ Dormant |
| Mar | — | 4.4" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| May | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jun | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 6" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 5.4" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Nov | — | 4.1" | 0" | ❄️ Dormant |
| Dec | — | 3.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Putnam County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion Planting Timeline — Putnam County, TN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 6 | Mar 6 – Mar 20 |
| Transplant Outdoors | April 10 | Apr 10 – Apr 24 |
| Direct Sow | March 27 | Mar 27 – Apr 17 |
| Harvest | July 10 | Jul 10 – Aug 28 |
| Fall Sowing | August 17 | Aug 17 – Aug 31 |
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 | — |
| 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 7a
📆 Growing Season
199 days in Putnam County
Growing Tips for Putnam 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 Putnam County, TN?
Putnam County is in Zone 7a with an average last frost of April 10. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Putnam County, TN?
Putnam County, Tennessee is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 26.
Your Putnam County Garden Planner — Free
A 22-page printable planner built for Putnam County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.