Want to Nurture Wildlife? Plant a Native Oak.

Fall is the time to a plant a native oak tree that will benefit thousands of wildlife species for the next century or more

By Doreen Cubie
Habitat Gardening
Sep 26, 2024

Scarlet oaks (above) and other native oaks support an astonishing diversity of wildlife, from eastern chipmunks (below) to more than 1,000 caterpillar species (such as the spiny oak slug moth caterpillar, bottom).

FOR GARDENERS WHOSE GOAL IS TO HELP WILDLIFE, planting an oak tree is a no-brainer. “Native oaks are the most valuable tree for wildlife in 84 percent of the counties in the United States in which they occur,” says Doug Tallamy, a University of Delaware entomologist and author of the 2021 book The Nature of Oaks.

Based on Tallamy’s research, the National Wildlife Federation’s Garden for Wildlife® program features oaks on its online lists of keystone native plants for 10 North American ecoregions. A small subset of all kinds of native plants, keystone plants are those that are vital to the life cycles of many different wildlife species and therefore to the food webs that support entire ecosystems.

One of oaks’ most important benefits, Tallamy says, is that they are the host plants for more than 1,000 kinds of moth and butterfly caterpillars. These Lepidoptera larvae, in turn, are the most important protein that virtually all parent songbirds need to successfully raise their offspring—from cardinals and chickadees to wrens, vireos and thrushes. By contrast, native birch trees host just over 400 caterpillar species, while elms host about 200.

Each spring, scores of warblers, orioles, buntings and other long-distance migrants also flock to oaks to glean the caterpillars that will fuel their northward journeys. In fall, oaks produce copious amounts of nutritious acorns that feed dozens of other wildlife species, including deer, foxes, turkeys, chipmunks, javelinas, squirrels, woodpeckers, blue jays and wood ducks.

An image of an eastern chipmunk gathering acorns.

Before planting, make a plan

Except in the coldest regions, autumn to early winter is usually the best time to plant an oak. Make sure you choose a native species. Because this country is home to some 90 different kinds of native oaks, it’s important to “do some research before you decide what type of oak to plant,” says Joe Herring, a forester with the Iowa Department of Natural Resources. “University extension can be a good place to start.”

Native plant nurseries also can help guide the selection process. Another resource is NWF’s Native Plant Finder, an online tool allowing you to enter your zip code to learn what oaks are native to your area and how many butterfly and moth caterpillars each species supports.

Some gardeners have space for a large tree, such as southern live oak or shingle oak, which can reach 75 feet or taller. Others should stick with small to intermediate species. Some smaller varieties, which average 25 feet or less, include dwarf chinquapin oak, bluejack oak, dwarf live oak and scrub oak. Intermediate trees, which mature at about 30 to 50 feet, include blackjack oak, swamp chestnut oak, scarlet oak, Gambel oak and overcup oak.

Another consideration is that some oaks begin producing the acorns that feed wildlife sooner than others, says Herring. Dwarf chinquapin oak starts yielding acorns almost immediately, for example, while chestnut oak does not churn out a bumper crop for 15 years or more.

Ready-to-plant oaks are widely available from nurseries, either in containers or as balled-and-burlapped trees, with container trees being smaller and easier to transport home and transplant into the ground. Another option is a bare-root tree—already a foot or so high, with no dirt around its roots—but these should be planted very soon after purchase, generally in the spring.

According to Tallamy, “one of the best ways to grow an oak tree is to plant an acorn or two in the fall.” Just make sure the nuts have come from a native tree. As soon as the acorns start to drop, he says, gather the freshest ones, preferably from under an oak growing near your house. You can even take them off the tree, Tallamy says. Just remove the caps from the nuts and plant them in a deep pot with a mixture of potting soil and local soil. Place the pot in a semiprotected area where squirrels and mice will not get to it. Water once a month or so and, come spring, when the acorn has sent out its first true leaves, transplant the tiny tree in the ground. In many cases, you’ll need to put a screen over the seedling to keep deer from devouring it.

An image of a spiny oak slug moth caterpillar.

Keeping oaks healthy

An important factor to consider when planting an oak is the potential for disease. Along the Pacific Coast, a deadly affliction known as sudden oak death syndrome is devastating the trees, says Larry Costello, co-author of the 2011 book Oaks in the Urban Landscape and owner of Oracle Oak Nursery in Northern California. Scientists believe the pathogen, a microscopic funguslike organism, was inadvertently introduced into the United States from Asia by way of nursery trees (not necessarily oaks) sometime in the 1990s. “Some species, like coast live oak, are very susceptible to sudden oak death,” Costello says. “Valley oak and Oregon white oak are not susceptible” so are good choices to plant in California and Oregon.

In the Midwest and Texas, oak wilt is a common disease caused by a fungus that kills oaks. “The best way to avoid it,” Herring says, “is to limit any pruning of your oak to late winter, before the growing season starts.” Red, black and pin oaks are more susceptible to the disease than are other native species. It’s always a good idea to check with your university extension office for disease-prevention guidance, he adds.

Despite such possible challenges, Tallamy stresses “there is no better tree to grow than an oak” to support both native wildlife and the complex ecosystems they inhabit. “Oaks live a very long time,” he says, averaging 100 to 300 years. “Plant for yourself and for future generations.”

Doreen Cubie is a science writer based in Arizona.