The Best Sweet Potatoes to Grow in Tennessee

For most Tennessee gardens, a fast-maturing, orange-fleshed variety like Beauregard or Georgia Jet is the safest pick. Summers are hot enough for sweet potatoes, and the season is long enough for types that finish in a reasonable time. Longer-season purple and white-fleshed types can work, but they leave little margin if the slips go in late or October turns cool.

The short answer for Tennessee

Choose by type, not by catalog photo. Fast orange types (Georgia Jet, Beauregard) suit nearly everyone, including beginners and gardeners at higher elevations. Orange types reward gardeners who get slips in the ground soon after the soil warms. Purple and white-fleshed types are for gardeners who can plant early and watch the weather in the fall.

The reason is how the crop grows. Sweet potatoes are frost-tender, so slips go in only after spring freezes are over. The roots then swell through the summer heat and have to be dug before the first fall freeze. At the Nashville reference station, NOAA’s 1991-2020 normals put the 30 to 70 percent probability band for the last 32°F freeze at March 31 to April 12. The same band for the first fall freeze runs October 28 to November 8. Those are probabilities for a freeze at or below 32°F, so a late cold snap after April 12 is still possible.

Heat is not the limiting factor. The reference station averages 40 days a year at 90°F or more, which is the kind of summer sweet potatoes grow best in. Season length decides which type you can grow. Maturity times are counted from transplanting the slip, and they run from fast types to slow ones.

For exact planting windows, see When to Plant Sweet Potatoes in Tennessee. The broader growing basics are in Growing Sweet Potatoes in Tennessee.

What will not work here

Slow varieties planted late are the most common failure. A purple type set out late has no spare weeks, and a cool fall can end the season before the roots have sized up. The first fall freeze band opens October 28 at the Nashville station, and gardens on higher or cooler ground can expect it sooner. Anyone planting after a spring crop comes out should pick a fast orange type.

Planting slips on the first warm weekend in spring also fails. Soil that is still cold and wet stalls the slips, and a freeze after the April 12 end of the band will kill the tops. Warm days in March and early April say little about the soil. Wait until nights stay mild and the soil has warmed.

Can a weekly watering routine backfire?

It can, because the summer is not dry. The Nashville station averages about 12.3 inches of rain across June, July and August (50.5 inches over the year). June gets 4.36 inches, July 4.16 and August 3.79, so August is the driest month, and it is still not dry. On paper that is around an inch a week. In practice much of it falls in thunderstorms that run off rather than soak in, and the 40 days at 90°F or more pull moisture out of the soil quickly.

The result depends on the soil. Sandy ground drains within the day and can need water between storms. Heavy clay holds a storm’s rain for a week. Adding a fixed weekly soak on top of that rain can crack the roots and invite rot. Established vines tolerate dry spells well, so water mainly during the first couple of weeks after transplanting and in a real drought. A straight-sided can or a rain gauge set in the bed will tell you what the sky delivered.

What does close spacing do in a humid summer?

It keeps the leaf canopy wet for longer and slows drying after every storm. In humid summers, tight rows breed fungal trouble and leave little room for air to move. Give each slip space, and more for vigorous types. Planting on raised ridges also helps heavy clay drain, and it gives the roots loose soil to swell into.

One last failure shows up in the fall. Leaving roots in the ground through a hard freeze shortens their storage life. If frost blackens the vines before you have dug, harvest soon after and do not leave the roots sitting in cold, wet soil.

What changes across Tennessee

Tennessee is not one garden. On the USDA Plant Hardiness Zone Map (2023, based on 1991-2020 normals), the state runs from zone 5b to 8a. That system is built on a single variable, the average annual extreme minimum temperature, so it describes winter cold. Sweet potatoes are grown as annuals and do not need to survive winter, but a spread that wide still tells you that spring and fall arrive at different times across the state. There is no single answer for every county.

The frost dates quoted here come from Nashville, the reference city. East Tennessee and the Cumberland Plateau are cooler and run later in spring than Nashville. Gardeners there should expect the last freeze to come later than March 31 to April 12, and the first fall freeze likely arrives earlier. That narrows the season from both ends.

If you garden in the north, on the Plateau or at altitude, shift three things. First, favor the fast orange types over the mid-season and slow ones. Second, warm the soil before planting, with raised ridges or black plastic laid ahead of time. Third, plant a little later rather than earlier, because slips set into cold soil gain nothing. Then plan to dig ahead of the first freeze.

Gardeners at the warmer end of the range have more room. A mid-season or slow type becomes realistic when planting happens on time and the fall stays mild. Which zone applies to your address is something to read off the USDA Plant Hardiness Zone Map by entering your ZIP code, rather than guess from a neighbor’s garden.

Where to check this for your own county

Your county office of University of Tennessee Extension is the next stop. Every county has one, and the staff know the soils, the frost pockets and the local summer pattern.

Ask for two things in particular. The first is the local planting calendar for sweet potatoes, which will give dates fitted to your county rather than a statewide average. The second is the list of varieties that have been trialed in your county or a nearby one, since a variety that performs well in one part of the state can disappoint in another. It is also worth asking where local growers buy certified slips, and whether the office offers soil testing before you set out a bed.

A county recommendation beats a state one. A statewide guide averages a lot of ground, from the river lowlands to the Plateau, and the closer a recommendation sits to your soil and your weather, the more reliable it is. Treat the types and dates here as a starting frame, and let the county office correct them.

Checking this against your own garden

Your own observations outrank any date in print. Three are easy to make with no equipment beyond your hands and a can.

• Soil warmth by feel. Push your hand a few inches into the bed on a spring morning. If it feels cool and clammy, wait. If it feels comfortably warm, the slips will root quickly. A bed that warms earlier than your neighbor’s has a sunnier or better-drained microclimate.
• The first new leaves on the slips. Fresh leaves after transplanting mean the slips have rooted. If they sit unchanged, the soil is probably too cool or too wet, and the site may hold cold air.
• The first frost on tender plants. Note the date frost first blackens tomato or basil leaves in your yard each fall. Over a few years that tells you when your garden’s freeze really arrives, and it is the signal to dig the sweet potatoes.

Write the dates down for a few seasons. The pattern in your notebook will beat the statewide bands, and it will tell you whether a slower variety is worth trying on your ground.

Common questions

What is the best sweet potato for a first-time grower in Tennessee?

A fast orange-fleshed variety such as Georgia Jet or Beauregard. They mature from transplanting, which leaves a cushion against a late spring or an early fall freeze.

Can I grow purple sweet potatoes in Tennessee?

Yes, but they need a long season from transplanting. Plant early, choose a warm site, and be ready to dig before the first freeze. At higher elevations or in the cooler parts of East Tennessee, the margin is thin.

How often should I water sweet potatoes in a Tennessee summer?

Water the slips during their first couple of weeks, then mostly leave established vines alone. Summer rain averages about 12.3 inches across June through August at the Nashville station, though it often arrives in storms. Water in a real dry spell, and more often on sandy ground than on clay.

When should I dig sweet potatoes?

Before the first freeze, which falls between October 28 and November 8 at the Nashville reference station in the 30 to 70 percent probability band. Gardens on cooler ground should expect it earlier. If frost blackens the vines first, dig soon afterward.