Ask Mr. Smarty Plants

Carya illinoinensis (pecan) can certainly be grown in Tennessee. This USDA Plant Profile does not show them growing in the extreme northeastern tip where Washington County is, but we believe that they probably would flourish there if the soils are moist. However, don't buy the ingredients for pecan pie quite yet; the tree is slow-growing, tends to bear nuts in alternate years and will not ordinarily begin bearing until it is 15 to 20 years old. The best nut production is on trees 75 to 225 years old. Here are the Growing Conditions from our Native Plant Database:

Water Use: High
Light Requirement: Sun
Soil Moisture: Moist
CaCO3 Tolerance: Low
Cold Tolerant: yes
Soil Description: Rich, moist, well-drained soils. Sandy, Sandy Loam, Medium Loam, Clay Loam, Clay, Caliche type
Conditions Comments: The sweet, edible nut, makes pecan the best hickory for fruit production. The tree does not bear liberal quantities of fruit in the northern part of its range, but makes an interesting ornamental there. Susceptible to galls, twig girdlers, aphids, borers, weevils, pecan scab, tent caterpillars, and webworms. Slow-growing. Difficult to transplant because of a large taproot.

For more information, see this Floridata website Carya illinoinensi. As mentioned above, the young tree has a long taproot which, if damaged, could result in the death of the tree. So, you are going to have to begin with a very small tree, and let it grow quite a while before you can expect a crop. When it does begin to bear, you can expect small seedlings popping up everywhere, mostly planted by squirrels. They and other small mammals, even some birds, are going to be waiting for those nuts, too. The tree gets quite large and is not a good selection for a small yard. 

From our Native Plant Image Gallery

Carya illinoinensis

Carya illinoinensis

Carya illinoinensis

Carya illinoinensis