Tree · Fagaceae
Southern Live Oak
Quercus virginiana
A sprawling, long-lived shade tree that wants room to grow and little else once it settles in.
Full sun
Every 7–14 days
USDA 8–10
40–80 ft · 12.2–24.4 m
Overview
The Southern live oak wears a low, dense crown carried on thick, near-horizontal limbs that reach out wider than the tree stands tall. Its leaves cling on right through winter, so the canopy stays green and full while other oaks go bare, and the old foliage lets go only in spring as the new flush unfurls to take its place. Grown for decades, the trunk thickens and the limbs sweep down close to the ground.
Come spring the branches hang with easy-to-miss catkins, slim and pale, before the acorns set. By fall those acorns ripen to smooth brown nuts and drop beneath the tree, and long gray strands of Spanish moss often trail from the outer limbs. It roots down through sand, loam, or clay, takes coastal salt on its leaves, and rides out drought once established, hardy across USDA zones 8 to 10.
Everything about the tree is built on scale. The crown alone can spread 40 to 80 feet (12 to 24 m) across, a broad dome of overlapping branches thrown out on heavy horizontal limbs. Those limbs run so far and hang so low that the tree needs bare, open ground around it, well clear of the house, the sidewalk, and the power lines.
Care
The short version: it wants full sun and almost any soil, regular water only while it is young, and a careful summer prune to hold off oak wilt, and past that it carries itself.
Light
In full sun a live oak fills out its densest, most even crown, the branches packing tight and the leaves closing over into solid shade. It will still leaf out in partial sun or light shade, but a tree in the open builds the fuller, rounder dome.
Water
A young tree drinks on a regular schedule, roughly every 7 to 14 days, while its roots spread and take a grip in the ground. Once settled, a mature live oak turns highly drought tolerant, its deep roots pulling moisture with little help from you.
Soil
Its roots take almost any ground you give them. They thread through sand, loam, or clay, hold in acidic or alkaline soil from pH 5.0 to 7.5, sit through the odd wet spell, and shrug off coastal salt. The tree grows fullest in moist, well-drained, slightly acidic soil.
Temperature
The foliage and wood ride out a wide swing, from about 10°F to 100°F (-12°C to 38°C). That covers the beating summer heat of the South and the occasional hard freeze that bites at the cool edge of its zones.
Humidity
The leaves ask nothing of the air around them, so there is no humidity target to hit. The tree grows wild in the muggy coastal South, where the air hangs thick and damp.
Feeding
A grown tree in fair soil pulls what it needs from its own roots and wants no feeding at all. Only a stalled, thin canopy calls for a balanced slow-release tree fertilizer in spring.
Pruning
Make cuts in mid to late summer, when the beetles that carry oak wilt to fresh wounds are least active. Clear out the dead, crossing, or weak branches and shape sound limb structure while the tree is young, since heavy cuts into an old trunk are best left alone.
Repotting
A live oak has no future crammed in a pot, its roots soon circling the wall. Ease it out of the nursery container and into open ground before that starts, and once it is planted, it holds that ground for life.
Size & spacing
This tree climbs 40 to 80 feet (12 to 24 m) tall and throws a crown that spreads 60 to 120 feet (18 to 37 m) across on long, low limbs. Give it that full stretch of open room, well away from buildings, walks, and utilities.
When to plant
A tree that grows to this bulk is in no hurry, and there is no tight season to hit. Set a young live oak out in fall or early spring, while the soil turns easily and the roots reach out before summer heat or hard cold. The blooms are slim, easy-to-miss spring catkins, and the smooth acorns ripen and fall in autumn.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Fall or early spring
- Harvest: Inconspicuous spring catkins; acorns mature in fall
Hardiness
USDA hardiness zones: 8–10
Temperature: down to -12°C
Troubleshooting
A sound live oak shows few flaws, and most of what marks the leaves and twigs is skin-deep rather than serious. The one problem to read carefully is oak wilt, the reason the pruning window sits where it does. Match the sign you see below before a single cut goes in.
Leaves curling and browning as the crown thins
Leaves that go limp and brown while the crown thins out point to oak wilt, a fungus that clogs the tree's water-carrying vessels from within and creeps through the canopy limb by limb. Split the wood and you find it stained with dark streaks, and the dieback marches from one branch to the next. Nothing turns it back once it is inside, so confirm it through an extension office or lab, keep any cutting to mid to late summer, and sever the underground root grafts to nearby oaks where advised.
Fix:
- Avoid pruning during active beetle season; prune only in mid-to-late summer
- Remove and properly dispose of infected trees per extension guidance
- Sever root grafts between adjacent oaks where recommended
Rounded bumps and raised blisters across the leaves
The small round swellings studding the leaves and twigs are insect galls, knots of tissue the tree throws up around gall wasps or mites, while the puckered, raised blisters on the leaf surface come from a fungus called Taphrina. Both stand out against the foliage, yet neither cuts into the tree's health. Rake the spotted, fallen leaves away to thin the blister, and let the galls sit, since a strong oak wears them without any cost.
Fix:
- Tolerate galls, which rarely harm the tree
- Rake and remove fallen infected leaves to reduce leaf blister
- Maintain tree vigor with proper watering
Toxicity
For all the beauty of its broad crown, the tree carries tannins in its acorns, buds, and young leaves that are not safe to eat. Dogs and cats that nibble them get an upset stomach, while horses and grazing livestock that eat a lot risk serious, sometimes fatal kidney damage. Keep animals from feeding on the fallen acorns and clippings, especially in fall.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A leaf or acorn taken by a curious cat leaves it with an upset stomach, bringing on vomiting, loose stool, and a day or two of nosing away from the bowl. The bout clears by itself as a rule, though the belly stays tender through it.
Dogs Mild
Acorns and foliage crunched up by a dog bring vomiting, diarrhea, and a flattened appetite. A whole acorn swallowed down can wedge in the gut and block it outright, so a dog that strains or keeps retching belongs at the vet.
Horses Severe
Horses take the tannins hard once the amount climbs. Colic and a churning stomach show up first, and a heavy feed of acorns or fresh young leaves can scar the kidneys deeply enough to kill.
Rabbits Toxic
Oak makes no fit forage for a rabbit. A rabbit's gut runs on a steady feed of mild greens, and the tannins packed into the leaves and acorns throw it off, so keep clippings and dropped acorns clear of the hutch and run.
Livestock Severe
Cattle, goats, and sheep cropping acorns and buds by the mouthful carry the gravest risk. Hard, bound-up droppings turn to dark, bloody diarrhea, and in the worst of it the kidneys shut down for good.
Birds Caution
Wild birds crack open whole acorns and come to no harm, yet the raw tannins bite at the smaller frame of a pet bird. Keep oak leaves and whole acorns well away from cage birds and pass them nothing off the tree.
People Caution
A raw acorn tastes sharply bitter from its tannins and can turn the stomach, so it lands on no plate as it is. Only a long soak leaches it edible, so keep small children from mouthing the fallen acorns off the ground.
Keep pets and livestock from grazing on fallen acorns, buds, and leaves, particularly in fall.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Most live oaks are the plain species, though a couple of selected forms exist, each drawing a slightly different crown shape.
Cathedral Oak
This selected cultivar is grown for the even, symmetrical dome its rounded crown draws as it matures.
Highrise
Its outline rises taller and narrower than the usual broad, sprawling form, drawing a slimmer silhouette for a tight space.
How to propagate
Live oaks rise freely from their own acorns, and the only real catch is timing, since the smooth brown seed will not wait around.
SeedEasy
Sow fresh acorns in fall as soon as they mature · Germinates within weeks to a few months; several years to a sapling
Live oaks come up freely from their own acorns, the smooth brown nuts that ripen and drop in fall. Gather them fresh and sow them at once, because a dried or stored acorn loses the ability to sprout. A fresh one pushes a root out within weeks to a few months, then spends several years of slow, patient growth swelling into a sapling.
Myths
Spanish moss trailing from a live oak is a parasite that slowly kills the tree.
The gray, hanging strands of Spanish moss are an epiphyte, hooked over the branches only for a grip and drawing their moisture and nutrients out of the air. They take nothing from the tree and do it no harm, so the trailing curtains can stay put.