Native Trees in Landscaping: Why They Outperform Non-Native Species
Native trees require half as much maintenance as exotic ornamental trees․ Native trees have adapted over thousands of years to Tennessee's clay soils and its natural humidity and freeze-thaw temperature changes․ They're less thirsty‚ less buggy and‚ best of all‚ they look like they belong․ If you're thinking of adding a plant or two to your property‚ you can't do better than a native․ It'll save you money and headaches for decades․
What Makes a Tree Truly Native?
A tree is native in a place when it occurs there as part of the area's flora and was not introduced there by people․ In Tennessee the Eastern Redbud‚ Flowering Dogwood‚ Tulip Poplar‚ Sugar Maple‚ and Southern Sweetbay Magnolia are native․ Native trees co-evolved with local soil microbiota‚ insects‚ and rainfall over thousands of years of natural selection․
Most of Tennessee is in USDA Hardiness Zones 6b-7b․ The east mountain region has a 6a designation‚ while the Mississippi River corridor in West Tennessee is in zone 8a․ Here‚ the trees from our own range grow into the heat and humidity of summer and the cold spells of winter without the leaf scorch and dieback that often afflict non-native trees and the delay before spring emergence․
Real Water Savings‚ Not Just a Talking Point
The rooting pattern of a native tree is more likely to follow the local rainfall pattern than the tropical irrigation practiced by the nursery grower or the planting zone of the person that plants them․ During its first two years‚ a young Eastern Redbud should be watered deeply once a week․ Further‚ the plants' well-rooted habit and Tennessee's 50+ inches (/year) of average annual precipitation render them largely drought resistant without additional watering‚ unlike many other ornamental plants imported from less hospitable locales which may require five or more years of routine watering before becoming self-sufficient․
Deep-rooted native trees‚ such as Tulip Poplar and Black Gum‚ hold soil in place on the rolling slopes many properties in Middle and East Tennessee include‚ far more effectively than shallow-rooted exotic trees․
Supporting Local Wildlife Is No Longer Optional
Instead‚ it is more accurate to say that native plants are sometimes the only trees a given species can eat․ According to University of Delaware entomologist Doug Tallamy‚ native oaks host over 500 species of caterpillars that serve as food for insectivorous birds‚ whereas non-native ginkgo and Bradford pear support fewer than five species of caterpillars․ And without caterpillars for the babies to eat‚ chickadees‚ warblers‚ and dozens of other backyard birds would not have a successful nesting season․
Serviceberry‚ native dogwood and native oaks especially take care of pollinators in spring‚ songbirds in summer‚ and offer berries and acorns that are used by many birds and mammals through to winter․ And ecologically‚ for any planting done for birds and butterflies‚ they're not just a good idea - they're close to essential․
Carbon Storage and Cooling: The Practical Climate Case
An established native shade tree can reduce the temperature of that air space by 10 degrees or more․ In a community setting‚ this can save summer air-conditioning costs if these trees are established on the south and west sides where they will be effective in blocking afternoon sun from buildings․
Fast-growing native trees (those attaining shade in 8-10 years)‚ such as Tulip Poplar (Liriodendron tulipifera)‚ which may grow 3-5 feet (1-2 m) a year‚ can provide maximum shade faster than slower-growing native trees‚ such as Sugar Maple (Acer saccharum)‚ which develop shade in 15-20 years or longer․ These are often dense‚ long-lived trees that may exceed 100 years of age․
Fall Color and Year-Round Interest
The reason is that Tennessee's native trees show some of the most beautiful fall colors Cool weather by night‚ and some soil chemistry‚ cause trees to produce anthocyanins and carotenoids‚ giving trees the reds and yellows of autumn foliage․ Sugar Maple also occasionally displays a bright orange-red color in autumn․ Black Gum‚ often one of the first to manifest fall color‚ takes on a deep scarlet sometimes as early as late September․ Sourwood also turns red early․
Spring blooming understory trees include white Flowering Dogwood and magenta Eastern Redbud․ Both bloom before they leaf out‚ brightening the still-bare ground‚ and prefer (but do not require) partial shade․ When used for layered plantings‚ they will be most effective under overstory trees rather than scattered along the edge of an open lawn․
Planting and Care Specifics
In most circumstances‚ autumn is the most favorable time for tree planting (October through early December in Tennessee) when roots grow in the cooler and moist environment before summer's heat․ If spring planting is necessary‚ March and April are most ideal when the air temperature does not exceed 80 degrees․
The hole should be twice as wide as the rootball and as deep as the rootball․ While non-natives are much more likely to be planted too deep‚ and while this is not permanent damage as with natives‚ the plant does take years to die after being planted too deep․ Fill the hole's sides with native soil (no compost)‚ so that the roots do not stay in the high-quality soil used for the hole but can grow into native soil․
Add a 2 to 3 inch (51 to 76 mm) thick ring of mulch out to the dripline 2 to 3 inches (5․1 to 7․6 cm) from the trunk (to prevent crown rot and protect against voles) and water weekly for the first 2 years‚ then less frequently when the roots are established․
Choosing the Right Native for Your Site
Not all native trees are appropriate for all landscapes․ Select trees to fit your site conditions:
Full sun‚ well-drained soil: Sugar Maple‚ Tulip Poplar‚ Black Gum - Partial shade or understory: Flowering Dogwood‚ Eastern Redbud‚ Sourwood - Wet or poorly drained areas: Sweetbay Magnolia‚ River Birch․ - Small yards or tight spaces: Serviceberry‚ Redbud (both under 25-30 feet in height)
TN Nursery will ship Tennessee native trees such as Flowering Dogwood‚ Eastern Redbud‚ and Sugar Maple that are suitable for home gardens rather than for commercial planting․ TN Nursery propagates and ships all trees dug and sized for home garden use․ Therefore‚ when you are buying native trees from TN Nursery‚ you are actually buying trees that are conditioned to grow in our climate and not just nursery plants․
The Bottom Line
Native trees are easier to live with over the long run․ They ask less of you and give you more in return: cleaner air‚ real wildlife habitat‚ lower water bills‚ a landscape that feels more a part of its place than a part of yours․ The math is pretty clear for the Tennessee homeowner: Go native․
