Some of the best trees to plant in Tennessee‚ for fall planting‚ along with when and where to plant․
If you're gardening in Tennessee‚ fall planting occurs anywhere between early September and early November‚ but most can be done six to eight weeks before your average first hard frost․ This gives roots a chance to settle in‚ and soils to cool down to the 50- to 65-degree Fahrenheit range where most trees and shrubs adjust so they can go dormant for the winter․ You will be planting into cold‚ waterlogged soil that will not support new root growth until warmer temperatures arrive in spring․
Tennessee lies in three USDA hardiness zones‚ a more important fact than most planting guides admit․ Most of the highlands of Gatlinburg and Johnson City in East Tennessee lie in USDA zones 6b to 7a․ It is anticipated that the first frost will occur by mid-October․ Middle Tennessee (Nashville area and surrounding counties) is in zone 7a‚ where it frosts in the last weeks of October or the first weeks in November․ West Tennessee‚ including the Memphis area‚ is in zone 7b to 8a and generally has a few extra weeks of the gardening season because frost rarely occurs before mid-November․ If you're still in doubt‚ check the USDA map for your county before purchasing your plant․
Why Fall is Better for Root Establishment
The secret of fall planting is that soil retains heat longer than air․ Therefore‚ although air temperature is dropping and thus putting stress on the top of the tree‚ the ground is still warm enough for root growth․ Roots will continue to grow for several weeks once the upper portion of the tree would be dormant․ The October tree is already rooting‚ the spring-planted tree is going into the ground‚ and by next summer the October tree is better able to withstand heat and drought stress‚ by virtue of having had a full winter and spring․
American Arborvitae: A Southeast Landscape Staple
Another one of the best plants for fall planting on Tennessee properties is the American Arborvitae (Thuja occidentalis) for anyone who wants a year-round privacy screen or windbreak: they prefer full sun to light shade and well-drained soil․ The quickest way to lose an Arborvitae in winter is by waterlogged roots․
Spacing is very important․ When used as a closely trimmed hedge‚ most arborvitae need to be planted 3 to 4 ft (0․91 to 1․22 m) apart‚ but 6 ft (1․8 m) apart when left to grow naturally․ Incorporate compost into the planting hole‚ back fill‚ and cover with two to three inches of mulch (but not against the trunk‚ as this causes it to rot)․ Water thoroughly twice a week for the first month‚ and weekly until November (less if meaningful rainfall occurs)․ TN Nursery ships arborvitae balled-and burlapped or in containers and the fall-shipped plants typically undergo less transplant shock than those shipped during the heat of July․
Willow Oak: Shade That's Built for the Long Haul
The Willow Oak (Quercus phellos) grows in all three zones of Tennessee․ It is a native Southeastern tree and fall is the best time to get it in the ground․ The trees are fast-growing for an oak tree and you won't have to wait 30 years for decent shade cover underneath your tree․ It tolerates urban planting‚ street trees and large residential lawns‚ the narrow leaves producing less of a fall leaf load than broadleaf oaks‚ which is a small detail appreciated by homeowners in November․
Willow oaks are adaptable to full sun or partial shade and most soil types and no particular soil pH levels․ This may account for the tree's adaptability to the variety of clays and loams that occur across Tennessee․ Water thoroughly immediately after planting and keep the root zone moist during the first six weeks․ Lightly prune broken or crossed branches in autumn‚ but wait until the tree is dormant in December or January to prune more heavily for shape or size control․
Box Elder: Fast Growth‚ Practical Value
Though often derided as a weed tree‚ the Box Elder (Acer negundo) can be used to create a slope stabilizer‚ or to provide fast shade on a property where shade is needed but the land owner realizes they don't want to wait a decade for the tree‚ and tolerates clay‚ sandy‚ and varying pH․ Best in full sun or partial shade․ Space them at least 15-20 feet apart‚ since they spread more laterally than vertically․ Once they are established‚ they will grow faster than either the arborvitae or the willow oak and may reach 3 feet in one season․
What Competitors Miss: Watering by Soil Type‚ Not Just Calendar
Most fall planting guides say to water regularly‚ but the soil from county to county in Tennessee is very different․ If you are planting in the heavy red clay of Middle Tennessee‚ water less frequently and deeper‚ as the soil retains water longer than the sandy soils in West Tennessee․ One of the most common mistakes in fall planting is overwatering clay-planted trees‚ but a better method may be to check soil moisture by sticking a finger 2 inches into the ground․
A Quick Word on perennials and shrubs
It's not just trees that can still be planted in fall․ Native perennial plants‚ ornamental grasses, and flowering shrubs can all be planted out in fall with established gardens; landscape beds around new trees should also be planted in fall to allow plants to become well rooted before the onset of spring growth․
Getting It Right Before First Frost
The most common mistake the average gardener makes when planting in fall is not following through with proper care of the tree after it is planted in the ground․ Water through November‚ unless you get regular rainfall‚ and do not fertilize until spring‚ after the new growth from the fall fertilizer has a chance to harden off before the cold weather arrives․ Proper care will make these trees the first to wake up in April‚ much earlier than those planted in April․
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