Knoxville, Tennessee: planting zone & frost dates
Knoxville is in USDA plant hardiness zone 7b, where the average coldest winter night reaches 5 to 10°F (-15.0 to -12.2°C). The typical last spring frost is around Apr 19 and the first fall frost around Oct 22.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Apr 29 | Oct 13 |
| Typical planning date (30% risk) | Apr 19 | Oct 22 |
| Median (50%) | Apr 11 | Oct 28 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station KNOXVILLE EXP STN, TN (USC00404946), 5.0 mi (8.1 km) from the city center and 56 ft lower than the city center (-17 m). Record used for the 1991–2020 normals: 30 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Knoxville
All 15 ZIP codes covering Knoxville are in zone 7b.
Vegetable planting calendar for Knoxville
Dates are counted from the 30%-risk frost dates above (last frost Apr 19, first frost Oct 22). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 22 – Mar 8 | Apr 26 – May 10 | — | — |
| Pepper | Feb 8 – Feb 22 | May 3 – May 17 | — | — |
| Lettuce | Mar 8 – Mar 22 | Apr 5 – Apr 26 | Mar 22 – May 3 | Aug 13 – Sep 10 |
| Green Beans | — | — | Apr 26 – May 31 | Jul 30 – Aug 13 |
| Sweet Corn | — | — | Apr 26 – May 24 | — |
| Zucchini & Summer Squash | Mar 22 – Mar 29 | Apr 26 – May 10 | Apr 26 – May 17 | Jul 30 – Aug 13 |
| Cucumber | Mar 22 – Mar 29 | May 3 – May 10 | Apr 26 – May 17 | Jul 30 – Aug 13 |
| Carrot | — | — | Mar 29 – May 3 | Jul 30 – Aug 13 |
| Onion | Jan 25 – Feb 8 | Mar 22 – Apr 5 | — | — |
| Potato | — | Mar 22 – Apr 12 | — | — |
| Basil | Mar 8 – Mar 22 | May 3 – May 17 | May 3 – May 24 | — |
| Spinach | — | — | Mar 8 – Apr 5 | Aug 27 – Sep 24 |
| Kale | Feb 22 – Mar 8 | Mar 22 – Apr 12 | Mar 22 – Apr 12 | Aug 13 – Sep 10 |
| Broccoli | Feb 22 – Mar 8 | Apr 5 – Apr 26 | — | Jul 30 – Aug 13 |
| Peas | — | — | Mar 8 – Mar 29 | Aug 13 – Aug 27 |
| Eggplant | Feb 8 – Feb 22 | May 3 – May 17 | — | — |
| Cabbage | Feb 22 – Mar 8 | Mar 22 – Apr 5 | — | Jul 30 – Aug 13 |
| Radish | — | — | Mar 15 – May 3 | Sep 10 – Oct 8 |
| Strawberry | — | Mar 22 – Apr 12 | — | — |
| Beets | — | — | Mar 29 – May 10 | Aug 13 – Aug 27 |
Nearby cities in Tennessee
- Chattanooga — zone 8a, last frost Mar 31, first frost Nov 3
- Murfreesboro — zone 7b, last frost Apr 15, first frost Oct 22
- Nashville — zone 7b, last frost Apr 7, first frost Oct 25
- Franklin — zone 7b, last frost Apr 10, first frost Oct 25
- Clarksville — zone 7b, last frost Apr 10, first frost Oct 27
- Memphis — zone 8a, last frost Mar 24, first frost Nov 9
More: all Tennessee cities · other zone 7b cities: New York, NY, Philadelphia, PA, Oklahoma City, OK, Nashville, TN, Washington, DC, Baltimore, MD, Albuquerque, NM, Tulsa, OK
Knoxville gardening questions
When is the last frost in Knoxville, TN?
Plan around Apr 19. At NOAA's Knoxville Exp Stn, TN station, 5.0 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 11, and after Apr 29 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Mar 31. The 90% and 10% dates are 34 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Knoxville, TN?
Start seeds indoors Feb 22 – Mar 8 and set transplants outside Apr 26 – May 10, once nights stay above 50°F and the soil is near 60°F. That leaves 186 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Knoxville?
About 198 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 176 days, and in 1 year in 10 it runs 220 days or more. In fall there is a 10% chance of frost by Oct 13 and a 30% chance by Oct 22. That is the shortest of the 7 Tennessee cities on this site.
When should I plant a fall garden in Knoxville?
Count back from the first fall frost (Oct 22): transplant broccoli Jul 30 – Aug 13; sow kale Aug 13 – Sep 10; sow lettuce Aug 13 – Sep 10; sow radishes Sep 10 – Oct 8. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 6. How the math works: succession and fall planting.
Did Knoxville's hardiness zone change on the 2023 map?
Yes. Most of Knoxville was zone 7a on the 2012 map and is zone 7b on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Knoxville compare with Asheville, NC?
Both are in zone 7b. The typical last spring frost in Knoxville (Apr 19) comes about 6 days later than in Asheville, NC (Apr 13), 83 miles away, and the first fall frost is Oct 22 versus Oct 26. Knoxville sits about 1,176 ft lower, which explains part of the gap. The two cities use different NOAA stations.