Frost dates for 37931Knoxville, TN
The average last spring frost in Knoxville is March 31 and the average first fall frost is November 4, giving a typical growing season of about 218 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 31
- Average first fall frost
- Nov 4
- Growing season
- 218 days
Safer after Apr 15 (1-in-10 risk)
Possible by Oct 22 (1-in-10 risk)
First frost typically in 1 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 28 · Apr 12 · Apr 30 | Oct 14 · Oct 27 · Nov 8 | 196 days | 100% |
| Frost / freeze (32°F) | Mar 11 · Mar 31 · Apr 15 | Oct 22 · Nov 4 · Nov 18 | 218 days | 100% |
| Hard freeze (28°F) | Feb 26 · Mar 18 · Apr 3 | Nov 1 · Nov 15 · Dec 4 | 243 days | 100% |
Planting calendar for Knoxville
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 28 – May 6 |
| Tomatoes | Transplant outdoors | Apr 16 – Jul 15 |
| Peppers | Start seeds indoors | Feb 28 – Mar 31 |
| Peppers | Transplant outdoors | Apr 30 – May 31 |
| Eggplant | Start seeds indoors | Mar 17 – Apr 15 |
| Eggplant | Transplant outdoors | Apr 30 – May 31 |
| Cucumbers | Sow outdoors | Apr 30 – Jul 25 |
| Summer squash | Sow outdoors | Apr 16 – May 31 |
| Winter squash & pumpkins | Sow outdoors | Apr 30 – May 31 |
| Snap beans | Sow outdoors | Apr 16 – Aug 17 |
| Sweet corn | Sow outdoors | Apr 16 – Jul 15 |
| Watermelon & cantaloupe | Sow outdoors | Apr 30 – May 31 |
| Okra | Sow outdoors | Apr 23 – May 16 |
| Peas | Sow outdoors (spring) | Feb 28 – Apr 15 |
| Potatoes | Plant outdoors (spring) | Feb 28 – Apr 30 |
| Onions | Start seeds indoors (spring) | Jan 17 – Feb 13 |
| Onions | Transplant outdoors (spring) | Mar 17 – Apr 15 |
| Broccoli | Start seeds indoors (spring) | Feb 10 – Mar 16 |
| Broccoli | Transplant outdoors (spring) | Mar 17 – Apr 15 |
| Broccoli | Start seeds indoors (fall) | Jul 5 – Jul 15 |
| Broccoli | Transplant outdoors (fall) | Aug 4 – Aug 15 |
| Cabbage | Start seeds indoors (spring) | Jan 31 – Feb 28 |
| Cabbage | Transplant outdoors (spring) | Feb 28 – Mar 31 |
| Cabbage | Start seeds indoors (fall) | Jun 25 – Jul 25 |
| Cabbage | Transplant outdoors (fall) | Jul 25 – Aug 25 |
| Leaf lettuce | Sow outdoors (spring) | Feb 28 – May 16 |
| Leaf lettuce | Sow outdoors (fall) | Jul 25 – Sep 10 |
| Spinach | Sow outdoors (spring) | Feb 21 – Apr 6 |
| Spinach | Sow outdoors (fall) | Aug 11 – Sep 15 |
| Radishes | Sow outdoors (spring) | Feb 28 – Apr 20 |
| Radishes | Sow outdoors (fall) | Jul 25 – Sep 25 |
| Kale | Sow outdoors (spring) | Mar 17 – Apr 6 |
| Kale | Sow outdoors (fall) | Jul 18 – Aug 25 |
| Carrots | Sow outdoors (spring) | Mar 31 – May 16 |
| Carrots | Sow outdoors (fall) | Jun 25 – Aug 10 |
| Garlic | Plant outdoors (fall) | Oct 25 – Nov 25 |
Where these dates come from
ZIP code 37931 is matched to the NOAA station Oak Ridge Asos, TN, 11.1 km away, at 910 ft elevation (133 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Oak Ridge Asos, TN (used) | 910 ft | Mar 31 | Nov 4 |
| Oak Ridge Atdd, TN | 905 ft | Apr 5 | Nov 1 |
| Knoxville Exp Stn, TN | 830 ft | Apr 11 | Oct 28 |
| Knoxville Mcghee Tyson Ap, TN | 962 ft | Apr 1 | Nov 2 |
Frost dates near Knoxville
- Knoxville, TN 37932 · last Apr 5, first Nov 1
- Powell, TN 37849 · last Apr 22, first Oct 25
- Clinton, TN 37716 · last Mar 31, first Nov 4
- Oak Ridge, TN 37830 · last Apr 5, first Nov 1
- Heiskell, TN 37754 · last Apr 22, first Oct 25
- Louisville, TN 37777 · last Apr 1, first Nov 2
- Oliver Springs, TN 37840 · last Apr 5, first Nov 1
- Andersonville, TN 37705 · last Apr 22, first Oct 25
Frequently asked questions
- When is the last frost in Knoxville, TN?
- For ZIP code 37931, the average last spring frost (32°F) is March 31, based on NOAA 1991-2020 climate normals for the Oak Ridge Asos, TN weather station. There is a 1-in-10 chance of a frost after April 15.
- When is the first frost in Knoxville, TN?
- The average first fall frost (32°F) is November 4. There is a 1-in-10 chance of frost by October 22, so tender plants are at risk from that point on.
- How long is the growing season in 37931?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 218 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.