One uplifting way to mark the hardships and sorrows of a year like no other is to plant a tree.
But don’t plant just any tree. Make it an oak.
With its deep cultural resonance as a tree that is steadfast, the oak plays out this indomitable spirit in the garden. The subtle ornament of its bark, foliage, acorns and restrained fall coloration all combine to make an oak greater than the sum of its parts. It is a friend that is solid, always available to be admired or to recede, always sheltering.
The planting of a small tree can be private and personal or a collective ritual but either way it is an act of commemoration and affirmation. From a practical standpoint, it’s probably best to delay your tree-planting ceremony this year until late summer in the Mid-Atlantic, after the periodical cicada fiesta.
In the meantime, you may want to pick up a copy of Doug Tallamy’s new paean to Quercus, “The Nature of Oaks.” Tallamy is an entomologist, best-selling author and established champion of the ecological value of native plants for landscape use.
As a tree that shelters other life, the oak is unmatched. “Oaks support more forms of life and more fascinating interactions than any other tree genus in North America,” Tallamy writes.
The acorn drop, prolific in some years, is a boon to some obvious customers — deer, possums, squirrels, bears, raccoons, mice and voles. Birds feast, too, including turkeys, woodpeckers, crows, titmice and blue jays. The jay buries the seeds in the ground for winter storage, though many sprout.
The oak’s value to migrating songbirds is even greater, if not as obvious. For reasons that aren’t clear, oaks are magnets for an extraordinary number of caterpillars. Tallamy writes that in his home county in southeastern Pennsylvania, 511 species of moths and butterflies rely on oaks, far more than any other tree. Many of the caterpillars are munching now and will continue into May, when the new leaves are fresh and tender. This coincides with nesting season for the birds, which ply their nestlings with a constant diet of protein- and fat-rich larvae. In his 10-acre lot, Tallamy has recorded many types of warblers as well as orioles, gnatcatchers, thrushes, kingbirds and buntings.
At a time when bird populations have dwindled markedly, planting an oak seems especially useful in creating an ecologically rich garden.
But planting the tree isn’t enough. How you treat what’s under an oak is also important. A sterile, thirsty and chemical-fed lawn is about the worst companion — better to plant perennial ground covers, and when the oak leaves drop in autumn, leave them in place. This allows the caterpillars to pupate in the soil beneath the tree, and countless organisms to live off the leaf litter and then the soil humus that it becomes.
Robust soil biology supports thriving plant life, even if this subterranean universe is mostly hidden from our eyes.
An oak planting would also improve the health of a sick planet. Tallamy says the oak’s dense wood and longevity make the tree an optimum choice for capturing atmospheric carbon.
This occurs not just through photosynthesis but the way the oak partners with a beneficial soil fungi named mycorrhizae, which develops over several years to effectively extend the root system of its host plant. In doing so the fungi produce a glue-like protein named glomalin, which itself becomes a significant carbon lock.
Tallamy anticipates common objections to oak planting. The yard is too small, people trip on acorns, a limb may fall on the house, the leaves have to be raked. To which Tallamy says, “Oh, sigh.”
Oaks grow broad in open, sunny locations, but in tighter, shadier quarters, their spread is contained. (Tallamy actually suggests planting groupings of two or three oaks, which will protect one another with interlocking root systems). Oak branches spread, of course, but lower limbs can be removed when young to guide the form of the tree.
Another complaint, paradoxically, is that a tree is too slow to grow, especially an oak. This is not the case. I visited Tallamy’s property just before the pandemic and was struck by a seemingly middle-aged white oak, more than 40 feet tall, outside his front door. This, he told me, was less than 20 years old, and planted from an acorn he had first placed in a pot.
Once the roots are established, some oaks can put on two feet of growth per year on the way to a height of 40 to 80 feet, depending on the variety and age of the tree. Among the speedy oaks are the common red and willow oaks, but others include the overcup oak, the shingle oak, the swamp chestnut oak and the Nuttall oak.
This leads to the next point. In the United States, we have an embarrassment of riches when it comes to indigenous oak species — a total of 91. Not all of them are suited to garden use (and some are threatened) but the homeowner should consider planting some of the more uncommon types.
Oaks divide roughly into upland and bottomland species, the former suited to difficult dry sites and the latter to areas that get soggy. Among my lesser-known favorites are the chestnut oak (Quercus montana), with distinctive toothed leaves and tolerance of dry soils; the swamp chestnut oak (Q. michauxii), with similar leaves but tolerance to wet soils; the overcup oak (Q. lyrata), with upswept branches and adaptability to soil conditions; the Shumard oak (Q. shumardii), handsomely compact and pyramidal when young; and the Nuttall oak (Q. nuttallii), whose attributes include rich, ruby-red fall coloration. Check suitability to your hardiness zone before selecting. (The quintessentially Southern species, live oak, will grow in Washington, by the way).
An oak quest will also turn up varieties of certain species and hybrids between species. Some of these include crosses with the English oak, something to consider if you only want a native species.
Tallamy and I are on the same page with this advice: There is no need to pay a high price for large caliper (trunks of two inches-plus) trees, which apart from the cost, are beasts to maneuver and plant and less likely to establish than smaller trees. After a few years, the small tree will soon match or surpass the stature of the big one.
“In a blink of time,” Tallamy writes, “they will be large enough and old enough to fully assume their keystone positions in our yard.”
Where to find them
A few native oak species and their varieties are generally stocked at independent garden centers, which may also be willing to order specific oaks. Get the smallest size you can find for ease of planting, the sake of your purse and tree establishment. Check with state and local native plant societies for a list of native plant nurseries in your area. Many societies sponsor springtime plant sales where saplings are sold.
Some public agencies and nonprofits will source and may subsidize shade tree planting, including oaks, as part of environmental programs related to home gardens, such as installing rain gardens.
Another option is to plant acorns, which become fast-growing trees once the roots are established. Species that belong to the white oak group (e.g. white oak, swamp white oak, swamp chestnut oak, overcup oak, chestnut oak and chinkapin oak) should be planted as soon as they drop. Those in the red oak group (e.g. northern red oak, Nuttall oak, pin oak, willow oak, Shumard oak, black oak and scarlet oak) need winter chilling before sprouting, and can be kept in a fridge until the spring, safe from animals, or potted up in the fall and kept outside. In either case, place the acorns in containers with well-draining potting soil. They must be protected from birds and mammals, including mice, and are best coddled in a pot for their first growing season. Once planted, make sure they are guarded against rabbits and deer.
In Virginia, regional native plant resources have been put together by a consortium called Plant Virginia Natives. In Maryland and Pennsylvania, the following nurseries specialize in native trees for pickup (most don’t ship) with a range of sizes and prices: Kollar Nursery, Pylesville, Md.; Clear Ridge Nursery, Union Bridge, Md.; Go Native Tree Farm, Lancaster, Pa.; Tree Authority, Perkasie, Pa.; Redbud Native Plant Nursery, Media, Pa.; and Edge of the Woods Nursery, Orefield, Pa. Call for availability, etc., before heading out. Saplings are probably too small to be affected by periodical cicadas.
Tip of the Week
Dandelions can be removed without herbicides by using a fishtail weeder. The taprooted weed is easier to remove when the soil is moist.
— Adrian Higgins
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