When to Plant Radish in Sullivan County, TN
Radishes are one of the fastest-growing vegetables, with some varieties ready in under a month. They come in round, elongated, and large winter types.
Sullivan County, Tennessee is in USDA Zone 7b. The average last spring frost is April 23 and the first fall frost is October 19, giving you a growing season of approximately 179 days.
At an elevation of 3,986 feet, Sullivan County receives approximately 46.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Radish during the growing season.
Sullivan County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-7.1
Drainage
Well Drained
Monthly Watering Guide for Radish
Radish needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Radish Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.9" | 0" | ❄️ Dormant |
| Feb | — | 3.3" | 0" | ❄️ Dormant |
| Mar | — | 4.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.3" | 1" | 💧 Light watering |
| May | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.3" | 1" | 💧 Light watering |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Sullivan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Radish Planting Timeline — Sullivan County, TN
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 9 | Apr 9 – Apr 30 |
| Harvest | May 7 | May 7 – May 28 |
| Fall Sowing | August 10 | Aug 10 – Aug 24 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Harvest |
| June | — |
| July | — |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
22–35 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 7b
📆 Growing Season
179 days in Sullivan County
Growing Tips for Sullivan County
Direct sow every 1-2 weeks for continuous harvest. Do not transplant. Harvest spring radishes promptly to prevent them from becoming pithy and hot.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Radish in Other Locations
Frequently Asked Questions
When should I plant Radish in Sullivan County, TN?
Sullivan County is in Zone 7b with an average last frost of April 23. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sullivan County, TN?
Sullivan County, Tennessee is in USDA Hardiness Zone 7b. The average last spring frost is April 23 and first fall frost is October 19.
Your Sullivan County Garden Planner — Free
A 22-page printable planner built for Sullivan County (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.