Red oaks and white oaks, and where each belongs

Red oaks have a fine bristle at the tip of each leaf lobe, or at the leaf tip on the unlobed species, and bitter acorns that take two seasons to ripen. White oaks have rounded or toothed lobes with no bristle, and sweeter acorns that ripen in one season. Every eastern oak belongs to one of two groups, and the group tells you more about how a tree will behave in your yard than the species name does. It sets when the acorns sprout, how fast the tree grows, how it handles the worst oak disease, how long it lives and what its wood is good for. Learn the groups first, then match the species to the ground.

Telling the two groups apart

Eight differences separate the groups, and the first one settles it on its own.

“White oak is slow-growing and long-lived (up to 600 years)” (USDA Forest Service, Fire Effects Information System, Quercus alba)

The bristle is the reliable test, and it sorts every species below.

What the split means for a planter

• Acorns. White-group acorns sprout as soon as they hit the ground in fall, root before winter and shoot in spring, so they cannot be stored dry and should be planted the week they drop. Red-group acorns need a cold, damp winter first, and can be kept moist in a refrigerator and planted in spring. Squirrels know the difference: they eat white oak acorns on the spot and bury red oak acorns for later. The split shows again at the other end of the dormant season, when the two groups break bud about a week apart.
• Lifespan. A white oak planted well can outlast every building around it.
• Wildlife. Both groups feed everything with a mouth, but white acorns go in fall and red acorns last into winter. Plant both and the table stays set for months.
• Oak wilt. Where the disease is present, favor the white group, and do not prune any oak from April through July, when the beetles that carry the spores are drawn to fresh cuts. Prune in the dormant season, at the collar.

“Oak wilt progresses quickly in red oak species, and trees do not survive.” (University of Minnesota Extension, Oak wilt in Minnesota)

Besides the common oaks at the end of this article, Blue Whale Trees grows the uncommon ones. Eight of them are described below, and five of those are sold as a set, the Rare Oak Collection: dwarf chinquapin, bear, sand post, Oglethorpe and delta post oak.

Bottomland and wet flats

Ground that floods in winter, clay that stays wet into spring, rich floodplain soil. Among the oaks we grow for it:

• Cherrybark oak (red group): the tallest and fastest of the southern red oaks, a straight-trunked giant for moist, fertile ground in full sun. Our line comes from a parent tree in Maryland, at the northern edge of the range. Not for a small lot. Zones 6 to 9, 80 to 120 feet.
• Swamp chestnut oak (white group): moist bottoms by preference, ordinary yard soil by tolerance, with some of the largest and sweetest acorns of any eastern oak and good fall color. Zones 5 to 9, 60 to 90 feet.
• Delta post oak (white group): a post oak that stands seasonal flooding on clay flats that bake in summer. Zones 7 to 9, 60 to 80 feet.
• Oglethorpe oak (white group): one of the rarest oaks in North America, at home on heavy, seasonally wet clay, with narrow unlobed leaves. It has grown well far north of its native stands. Zones 6 to 9, 50 to 80 feet.
• Overcup oak (white group): the white oak of the wettest ground, standing in floodwater for months on backwater flats and river bottoms, then taking compacted clay and a dry summer once established. The cup wraps nearly the whole acorn, so the nut floats, and unlike other white oaks the acorns wait until spring to germinate, one of the several ways floodplain trees survive high water. One of the tidier oaks for a wet lawn corner. Zones 5 to 9, 40 to 60 feet.

Swamp white oak takes the wettest ground of the common natives.

For the rest of a corner that drowns every spring, the Wet Spot Pack puts bald cypress and sweetbay magnolia with four shrubs that tolerate standing water.

Dry sand and ridges

Sandhills, gravel, thin soil over rock, hilltops the hose does not reach. The trick is to accept a smaller tree that will not die.

• Sand post oak (white group): a compact post oak of the driest coastal-plain sands, gnarled and built for heat. Zones 6 to 9, 15 to 40 feet. Hardiness north of zone 6 is untested.
• Bear oak (red group): the scrub oak of pine barrens and ridge tops, a shrub or small tree that resprouts after fire and feeds an outsized number of caterpillars. Full sun and poor ground. Zones 4 to 8, 6 to 20 feet.
• Dwarf chinquapin oak (white group): a true shrub oak for dry sandy or rocky slopes that bears sweet, low-tannin acorns within a few years of planting and suckers into a low colony. The oak for a small yard. Zones 4 to 8, 6 to 15 feet.

Post oak and blackjack oak, both common natives, take the poorest dry clay.

Two of these oaks come as a set for that ground: the Dry Sandy Site Pack pairs bear oak and dwarf chinquapin oak with beach plum, staghorn sumac, leadplant and black huckleberry.

The oaks everyone knows, which we also grow

Six of these seven are in our Classic Oaks group; scarlet oak is the one we do not grow. Most oak trouble starts with the wrong site, so each one’s needs are worth knowing:

• Northern red oak (red group): deep, well-drained loam on slopes and uplands; tolerant of city conditions; fast and eventually enormous.
• White oak (white group): deep, well-drained upland soil, acidic to neutral; resents compaction, fill and root cutting, so protect it during construction.
• Bur oak (white group): the most adaptable eastern oak, from bottomland to prairie, and one of the few that shrugs off alkaline soil and drought together.
• Willow oak (red group): moist, deep, acidic to neutral soil; a bottomland tree that accepts an average lawn but not a dry ridge.
• Pin oak (red group): wet, acidic soil and little else; it turns yellow on alkaline ground.
• Scarlet oak (red group): dry, sandy, acidic uplands; the best fall color among the common oaks.
• Chestnut oak (white group): dry rocky ridges and thin soil; slow, tough and long-lived; set beside chinquapin oak in chinquapin oak vs chestnut oak.

Common mistakes

• Pin oak on alkaline soil. The leaves yellow between the veins, the tree declines for decades, and iron treatments never fix it for long. Plant bur, chinquapin or swamp white oak instead.
• Willow oak on a dry hilltop. It is sold as tough because it tolerates average soil, but it is a bottomland tree, and on a droughty ridge it stalls and thins.
• A red oak in a small yard. A northern red or cherrybark oak wants a crown as wide as a house and becomes a problem tree within twenty years. Dwarf chinquapin, bear oak or sand post oak give you an oak that fits.
• Seed from far away. An acorn from the deep South grown in the North leafs out early and is likelier to be caught by frost. Choose seed from a climate like yours, and do not rule a species out because a range map stops one county short.

Most of those are site mistakes rather than oak mistakes. With a species in mind, the site check asks for your zone, the sun and soil moisture at the spot and the distances to wires and walls, then says whether that oak belongs there.

Put the six oaks recommended above on a request list, keep the ones that fit your yard, and we reply with what is ready and current pricing.

Common questions

How can I tell a red oak from a white oak?

Look at the leaf lobes: a fine bristle at each tip means the red oak group, and a rounded or toothed lobe with no bristle means the white oak group. The bristle test sorts every eastern oak.

Which oak group should I plant where oak wilt is present?

The white group, which usually loses a limb at a time over years and sometimes recovers, where a red oak dies within weeks. Prune no oak from April through July, when the beetles that carry the spores are drawn to fresh cuts.

Which oaks grow in wet ground?

Overcup oak stands in floodwater for months, and swamp chestnut oak, delta post oak and Oglethorpe oak take seasonally wet clay. Swamp white oak takes the wettest ground of the common natives.

Do deer prefer white oak or red oak acorns?

White oak acorns, which are less bitter: deer and most other wildlife eat them first and often finish them in fall. Red oak acorns last into winter and are eaten when the white ones are gone, so a planting for deer wants both.