Quercus rubra - Northern Red Oak

If you have space for just one shade tree, consider an oak! Botanists, foresters, and ecologists tend to rate oaks among the most ecologically important trees in North America - with around 90 species found across 85 percent of the nation's counties. They provide more food and shelter for wildlife than any other group of trees, making them "keystone species." Here in the “Keystone State”, where forests and woodlands are the default, nowhere is this more demonstrably true.

The environmental benefits of oaks don't stop there. Due to their size, habit, and longevity, they’re remarkably effective in managing erosion, buffering the worst effects of wind and storm runoff, and storing carbon. Of course, oaks are fantastic trees for use in gardening and landscaping which is our primary focus here.

Picturesque and attractive in habit and form, oaks make great focal points and specimens. They naturally and effectively anchor our manmade landscapes to the land. When sited properly, they buffer our homes and buildings from harsh winter winds and shade them from brutal summer heat. Most oaks are adaptable and extraordinarily resilient. Some are tolerant of extremes. Here at the nursery, it's rare for them to need warranty replacements.

In Pennsylvania and the Mid-Atlantic region, there are 20 or so native oak species. In nurseries, including ours, you’ll usually find even more, as well as various hybrids and cultivars. Because of this, there's an oak for almost any outdoor space.

Northern red oak (Quercus rubra) has long been a favorite among oaks in the landscape trade. It's fairly common in the wild, even amongst degraded woodlands, lending itself a reliable presence to wildlife across its native range. Some of this is likely due to its quick growth, enabling saplings to pass the deer browse line faster than many other species. It's also among the last trees with red fall color to drop its leaves. So, if you're driving on the highway and still see red trees in late October and November, you're likely seeing Northern red oaks!

Northern red oak's native range encompasses most of the eastern US and half of the Midwest, including every county in Pennsylvania. It can be found growing in well-drained lowlands to dry slopes and everywhere in between, revealing great versatility in gardening and landscaping. Other than highly compacted or extremely wet sites, Northern red oak will grow just about anywhere. It grows well in city environments although doesn't take well to alkaline soils. It also transplants easily, seldom going through prolonged periods of “transplant shock ". This tree holds up superbly against heat, cold, and windstorms. Because of its reliable adaptability, Northern red oak is a fine tree to plant in our gardens and landscapes.

While not flamboyant, Northern red oak is undeniably a handsome tree. It's also the state tree of New Jersey. In youth, bark is a smooth gray and becomes more furrowed with age, giving the appearance of what many naturalists describe as "ski tracks", which adds winter interest. Fall color is brilliant red. Oaks are usually one of the last groups of trees to change colors in fall, usually 2-3 weeks after maples do, prolonging autumn color.

Most oaks practice "marcescence" which means young trees don't drop their leaves till new leaves emerge in spring. On older trees, leaves on the bottom of the crown hold till spring while leaves higher up drop in fall. One theory that explains this phenomenon is it helps protect buds from herbivory. Regardless, this phenomenon adds winter interest to the tree by way of texture, color, and the sound of rustling leaves.

Oaks don't produce copious amounts of acorns annually. Instead, they choose to produce large quantities once every 2-5 years (provided they are pollinated by other oaks). Years of heavier acorn production are called "mast years." Oaks usually don't produce significant acorns until they're a couple decades old, and sometimes longer for Northern red oaks. While some see acorn production as a nuisance, we encourage you to think of it as providing a valuable resource to the animals and ecology of your yard and neighborhood. It's certainly wise, however, to carefully select a good site for any oak or other large tree. Maybe the middle of the lawn is a wiser spot than above the swimming pool, for example.

For the layman, oaks are generally organized into three categories: red oaks, white oaks, and live oaks. This helps with identification as well as care. Live oaks are typically evergreen that are found further south. All native oaks to Pennsylvania are in the red oak and white oak groups. Northern red oak, you guessed it, in the red oak group. Species in this group are identified by sharply cut and shaped leaf margins and indentations. They drop their acorns in fall and germinate in spring, providing a food source for birds and mammals throughout the winter.

The reason oaks are so well utilized is that while oak tannins are bitter, they aren't highly toxic or lethal. This is evidenced by the 500+ species of caterpillars of butterflies and moths that are supported by oaks. (Remember, if we want pollinators and healthy bird populations, we need caterpillars!). And of course, the acorns are rich in nutrients for mammals and birds. Acorns can be soaked and ground into flour to use in baking as well. Acorns of oaks in the red oak group typically have more tannins than white oak acorns which requires a lengthier soak to remove them.

The wood and branching structure of Northern red oak is very strong. Unlike rapid growing trees with brittle wood, such as willow and poplar, this isn't a tree that's prone to rotting, splitting, and falling on homes during windstorms. There is usually a trade off with wood strength and growth rate. Northern red oak strikes a terrific balance with its moderate rate of growth (one of the faster oaks) while not being inherently prone to structural deficiencies. That said, we advise planting large trees the radius of a mature crown away from structures. As this species typically matures at 50-70' wide in most landscapes, we suggest planting this tree no less than 25-35 feet from your house. Most oaks are long-lived in the wild, with Northern red oaks often living for 300 years or more. With the right conditions and care, it's possible your Northern red oak could achieve that lifespan too.

Despite being inherently hardy, some oaks in the eastern US have fallen prey to two introduced pathogens in recent decades: oak wilt and bacterial leaf scorch. To reduce the risk of introducing these pathogens into your tree, only prune (if you must at all) during the colder months (November through March). Pruning during the warmer months leaves open wounds that run the chance of attracting insects that might transmit these pathogens into the tree’s vascular system. Oaks in the red oak group are more prone to these pathogens than white oaks so it's imperative to bear this in mind.

Check out the beautiful mature Northern red oak growing behind the fence where we keep our bagged goods and sold material (opposite of the greenhouse)!

If deer are a problem for you, we recommend you provide your tree with protection, such as a metal cage, until the tree is large enough to not be severely damaged. Once the tree is tall enough that the cage can be removed, protect the trunk with a trunk protector to prevent damage from buck rub from September through December. Tree guards are usually no longer necessary when the diameter of the trunk at chest height is 5".

Written by Plumline staff and not AI.