Gardening in Tennessee

Hardiness zones in Tennessee

Tennessee spans four USDA hardiness zones: 6b, 7a, 7b, and 8a. The coldest zone in the state is 6b, and the mildest is 8a. A hardiness zone number is based on the average annual minimum winter temperature recorded for that area, not on summer heat or rainfall. Two gardens in the same state can sit in different zones because elevation and location both shift that winter low. Knowing your zone tells you whether a perennial, shrub, or tree is likely to survive winter outdoors where you live. It does not tell you how much rain falls, how humid your summer gets, or what your soil is like. Those factors matter just as much as the zone number when you choose plants. This state's climate data is drawn from 146 weather stations. That range reflects real variation across the state. Check your own zone by county or zip code rather than assuming the state average applies to your yard.

• Zone 6b
• Zone 7a
• Zone 7b
• Zone 8a

Frost dates

Frost dates mark when it's safe to plant outdoors and when the growing season ends. Across Tennessee, the average last spring frost falls between March 16 and May 22, depending on where you garden. That's a nine-week spread between the mildest and coolest spots in the state. In fall, the average first frost arrives between October 1 and November 16. These are long-term averages, so an actual frost can land earlier or later in any single year. Wait until after your local last frost date before you set out tender seedlings like tomatoes and peppers. Start watching the forecast again as your local first frost date nears, since an early cold snap can still damage plants that have not hardened off. Use the frost dates for your own county, not a single number for the whole state, since the two can be weeks apart.

Climate

Growing season length in Tennessee varies a lot from one part of the state to another. The data behind this page comes from 146 weather stations spread across the state, which is why the figures below cover such a wide range. The frost-free growing season runs as short as 132 days in the coolest spots and as long as 244 days in the mildest ones. That's a difference of nearly four months between the shortest and longest growing seasons in Tennessee. Hardiness zones across the state run from 6b up to 8a, meaning winter lows differ noticeably depending on where you garden. The last spring frost can arrive as early as March 16 or as late as May 22. The first fall frost can land anywhere from October 1 to November 16. Put together, these numbers mean a gardener in one part of the state may plant tomatoes weeks before a gardener elsewhere in Tennessee. None of these figures say anything about rainfall, humidity, or summer heat, since zone and frost data only track winter cold and season length. If you want a full picture of your local climate, pair this page's numbers with your own observations of rainfall and heat where you live. Always check figures against your specific county, since a single statewide number can hide a lot of local variation.

Season length

The length of the frost-free growing season tells you how many days you have between your last spring frost and your first fall frost. In Tennessee, that season runs from as short as 132 days in the coolest areas to as long as 244 days in the mildest ones. A gardener with a 244-day season can grow crops that need a long stretch of warm weather. A gardener with a 132-day season needs to pick faster-maturing varieties or start seeds indoors early. Check your local frost dates to find your own season length, then compare it to the days-to-maturity listed on a seed packet before you plant. A short season doesn't rule out a crop, but it does mean timing matters more.