North Florida and South Georgia are blessed with many species of native oak trees. Two species, dwarf live oak and running oak, form thickets from underground runners and may reach heights of only three feet.
Plant swamp chestnut oak to add diversity and bright fall color to your yard. Photo by Donna Legare.
Some oaks have limited distributions in North Florida. Cherry bark oak and chinquapin oak occur only in Gadsden, Liberty, or Jackson counties along the Apalachicola River.
Others have extremely strict soil requirements, occurring only in deep sand of either present day or ancient sand dunes or sea floors. These soils occur from the present-day coastline to north of Bristol and Blountstown. Drs. Robert Godfrey and Herman Kurz, in their book Trees of Northern Florida (1962), describe two types of sand, buff and white, with certain oaks preferring one or the other. Buff sand is common in inland Wakulla County with turkey oak, bluejack oak, and sand-post oak found growing there, among others. Coastal dunes consisting of white sand support Chapman oak and sand-live oak.
Of the 25 oak species native to our area, only about 10 may be found at local garden centers. Others may be obtained by special request. Usually, these ten species can grow on either dry buff sand, moist lowlands, or rich upland soils.
This young white oak was planted in 2018 to add diversity to Mary Kay Falconer’s Betton Hill’s yard. Photo by Mary Kay Falconer.
This young white oak was planted in 2018 to add diversity to Mary Kay Falconer’s Betton Hill’s yard. Photo by Mary Kay Falconer.
Most people think of live oak when planting an oak in our area for good reason. They are long-lived grand trees. But there are other equally stately and beautiful species that should be used more often, such as white oak, swamp chestnut oak (also called basket oak), Shumard oak, and southern red oak. Laurel oak and water oak are quite common in our area. They are often given a bad rap for weak wood, but both can be strong, healthy trees for at least 50 years, meanwhile providing food for insects, birds, and mammals.
In his recent book, The Nature of Oaks (2021), Doug Tallamy discusses the amazing diversity of animals, primarily insects, which depend on oaks. He writes that native oaks in our nation support 534 species of moth and butterfly caterpillars, more than any other group of trees. Ninety percent of these caterpillars are soft, juicy, high protein food for songbirds and their nestlings.
Native oaks harbor more than caterpillars. Acorn weevils, lacebugs, leaf hoppers, walking sticks, tree cattle, tree crickets, and many other species are part of a valuable ecosystem in the canopy over our heads, usually unnoticed by us. This rich diversity of insects becomes the base of a complex food web.
When choosing an oak to add to your landscape, remember that only native species harbor the huge food web in their canopies. A non-native Japanese saw-tooth oak may provide acorns for deer, but the space taken up by the canopy will be a dead zone for other life. Most native insects cannot utilize non-native plants, due to the presence of different chemicals in the leaves. They need native plants with whom they have shared an evolutionary history.
Leaves in the canopy are not the only valuable resource for wildlife. Oak leaves on the ground below an oak decay more slowly than most other tree species. This leaf litter provides housing, food, and humid conditions for up to three years for insects. For example, Tallamy writes that there can be 90,000 springtail insects in a square meter under an oak. Leaf litter mites may be 250,000 per square meter!
The precious leaf litter under your trees is also critical for giant silkmoth reproduction. After eating leaves in the canopy, the caterpillar drops to the ground to spend a year or two as a pupa hidden under the dead leaves. If your lawn grass extends under the canopy, it spells death for the future beautiful imperial or Polyphemus moth.
Three species of oaks are quite common in our region – live oak, water oak, and laurel oak. For a healthy urban/suburban ecosystem, diversity is key; try planting other species of oaks in your yard. Choose the best oak for your yard based on soil and moisture needs. Some species are very adaptable, others are not. Consider white oak, Shumard oak ,and swamp chestnut oak for their stunning fall color. Mature white oak and swamp chestnut oak also have attractive light gray shaggy bark. Southern red oaks are also stately.
Winter is the best time to plant a tree in our region, while the tree is dormant. Doug Tallamy states, “contrary to urban legend, many species of oak grow quite quickly.” Give your tree plenty of space. Plant three or more trees in a small grove for roots to interlock and create a stronger planting for hurricane survival.
Tallamy suggests planting acorns for the healthiest root structure but admits most of us want instant gratification and squirrels will not cooperate and plant them where we want them. The next best method is to plant an inexpensive bare root seedling or whip. These will also grow a healthy root system.
The third option is to purchase a small one-, three- or seven-gallon potted tree. Roots may be circling in the pot and should be spread out in the hole or pruned off. Circling roots can kill a tree after a few years or will not provide a solid foundation in hurricane winds.
Tallamy’s “bottom of the list” option is to plant an expensive three- to four-inch caliper oak from a large container. The root system will be so compromised that the tree will not have a long life. Unfortunately, government codes usually specify planting large trees for instant impact.
This winter, increase the biodiversity of our urban forest; plant some different oaks and become a part of Tallamy’s “Suburbia National Park.” Remember they must be American native species!