Tree · Sapindaceae
Red Maple
Acer rubrum
Fast, hardy, and endlessly rewarding, red maple sets fall ablaze with red and orange.
Full sun
Every 7–14 days
USDA 3–9
39–89 ft · 12–27 m
Overview
Red maple has spread across eastern North America for good reason, and growers keep coming back to it. It shoots up fast, roots into nearly any soil from clay to sand, and powers through cold as low as -40°F (-40°C). The name earns itself in every season, with red flowers breaking open in late winter, red samaras spinning down in spring, red leaf stems through summer, and a full-on red and orange finish in fall.
Here is where it really wins you over: it thrives in wet, tricky ground that stumps most shade trees, taking soggy soil and the odd flood in stride, which is why it flourishes in swamps and along streams as easily as in a yard. There is one thing to plan for. Red maple is a soft maple, so its speedy growth throws out brittle limbs that a hard storm can snap.
Hand it some space and it pays you back for decades. A mature red maple rockets past 40 feet (12 m) with a wide crown and shallow roots that spread fast and can heave a sidewalk or nick a mower. Plant it well clear of pavement and, once it takes hold, it asks for almost nothing while it grows into a showpiece.
Care
The short version: set it in full sun to part shade, in moist and slightly acidic soil, and keep the water coming while it is young. It barely wants feeding, but jump on early structural pruning so its brittle limbs stay storm-ready.
Light
Plant it in full sun and it really takes off, though partial shade suits it too. Pile on the sun and you get bolder fall color and a denser crown, so grab the most open spot you can.
Water
It loves moist soil and shrugs off wet sites and the occasional flood that would sink most shade trees. Keep young and street trees watered through dry spells, and once a tree settles in it powers through medium-to-wet ground all on its own.
Soil
Give it average, well-drained soil and it runs with it, adapting to clay, loam, and sand. Its sweet spot is moist, slightly acidic ground at pH 4.5 to 6.5, though. Push past about pH 6.5 and the leaves start yellowing as manganese and iron lock away.
Temperature
Cold barely fazes this tree. It cruises across a massive span from -40°F to 100°F (-40°C to 38°C), covering USDA zones 3 through 9, so winter almost never holds it back.
Humidity
Skip the humidity worries entirely. Everyday outdoor air does the job, since what really drives this tree is moisture at the roots, not in the air.
Feeding
An established red maple in decent soil hardly ever needs a feeding, which frees you up. If you do feed, reach for a balanced or low-nitrogen, higher-potassium mix in spring. On alkaline ground, tackle manganese chlorosis with soil acidification or a micronutrient treatment instead.
Pruning
Prune in late summer or fall to dodge the heavy spring sap bleeding maples are famous for, clearing out dead, weak, and crossing limbs as you go. Since the wood is brittle, aim your early cuts at narrow, weak branch angles that storms would rip loose.
Repotting
none
Size & spacing
Get ready for a big one: red maple commonly hits 40 to 70 feet (12 to 21 m) tall with a crown flinging out 30 to 50 feet (9 to 15 m). Give it real room and keep it well back from sidewalks and driveways, since its shallow roots buckle pavement as they push.
When to plant
Red maple is in it for the long haul, so its planting window stays refreshingly short. Get young trees into the ground in the mild weather of spring or fall and let the tree charge ahead. Then the payoff rolls in, with red flowers as early as late winter, samaras in spring, and that headline color in fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall
- Harvest: Red flowers late winter to early spring (roughly January-April); red to yellow samaras mature in spring; brilliant red-orange-yellow foliage in fall.
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
A thriving red maple rarely acts up, but a few problems are worth catching fast. Nearly all of them come down to soil gone too alkaline, a fungus lurking in the ground, or the tree's own soft wood. Match your symptom below and move on it early, before a small hiccup turns into a real hazard.
Whole branches wilting and dying on one side
This is verticillium wilt, a soil fungus that invades the tree's water lines and knocks out branch after branch. Peel the bark on a wilting limb and green-to-black streaks usually show in the sapwood, joined by undersized leaves and a heavy seed crop. No cure exists, so cut out and destroy the dead wood, disinfect your tools between cuts, and keep the tree watered so it can fight back.
Fix:
- Prune out and destroy (burn or landfill) dead branches; do not compost
- Disinfect tools with 10 percent bleach or 70 percent alcohol between cuts
- Water and fertilize with low-nitrogen, higher-potassium fertilizer to support recovery
New leaves flushing yellow between green veins
You are looking at manganese chlorosis, which kicks in when the soil pH climbs above pH 6.5 to 7.0 and locks up the iron and manganese the tree is chasing. Limestone, concrete, and over-liming near foundations and pavement usually drive it. Test the soil, push it back toward acidic with elemental sulfur, and hit it with chelated manganese or iron if the yellowing gets bad.
Fix:
- Test and lower soil pH toward slightly acidic with elemental sulfur
- Apply chelated manganese or iron as a soil or foliar treatment
- Mulch and improve drainage to reduce nutrient stress
Limbs tearing loose after ice, snow, or wind
Red maple is a soft maple with brittle wood, and its fast growth packs it with narrow, weak crotches that storms rip apart. Clear broken and hanging limbs right away with clean cuts, and call an arborist for the big or overhead stuff. Your winning move is early structural pruning, training one strong leader and wide branch angles so storms find far less to grab.
Fix:
- Remove broken and hanging limbs promptly with clean cuts
- Structurally prune young trees to favor strong, wide branch angles
- Consult an arborist for large or hazardous limbs
Toxicity
Growing it around cats and dogs? Go for it, since red maple is safe for both. The real watch-out is horses, and it is no small thing: wilted or dried red maple leaves destroy a horse's red blood cells and can kill within days. Keep horses well away from fallen branches, raked leaves, and prunings.
Toxic to
Horses · Rabbits · Livestock · Birds
Safe for
People · Cats · Dogs
Horses Severe
This is the serious one. Wilted or dried red maple leaves destroy a horse's red blood cells, and the first signs are weakness, a poor appetite, and a dull, flat mood. Watch too for brown or blue gums, red-brown urine, colic, and laminitis, and get a vet out fast, since death can strike within 18 hours to 10 days and pregnant mares may abort.
Rabbits Caution
No safe-feeding data exists for rabbits, and the same blood-cell toxin could hit them too, so keep red maple leaves and prunings clear of the hutch.
Livestock Caution
Cattle, sheep, goats, and other grazers should stay off wilted maple leaves and fallen branches, since the toxin that floors horses can reach related animals as well.
Birds Caution
Little is known about how birds react, so play it safe, treat the wilted leaves as a risk, and keep poultry and pet birds off raked clippings.
Cats None
The ASPCA rates red maple non-toxic to cats, so a curious nibble is nothing to sweat.
Dogs None
Dogs breeze past this tree with no trouble. It carries no toxicity for them, and gnawing a fallen leaf or samara will not make a dog sick.
People None
Red maple poses no real danger to people. It is not a food plant, but handling the tree, its leaves, and its seeds is completely harmless.
Horse owners must keep horses away from red maples and, critically, from fallen branches and raked or wilted leaves, which are the deadly form. Do not dump maple prunings or leaves where horses can reach them. The tree poses essentially no toxicity risk to cats or dogs.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
United Kingdom
Animal PoisonLine: 01202 509000 (fee applies)
Australia
Animal Poisons Helpline: 1300 869 738
Varieties
Most red maples you will chase down at the nursery are named cultivars, bred for knockout fall color and a clean, reliable shape. These are the standouts to hunt for.
October Glory
A grower favorite for its dependable red-to-orange fall color that fires up late and holds strong for weeks.
Red Sunset (Franksred)
One of the most planted maples anywhere, snapped up for its bold orange-red fall color on a vigorous, sharply upright tree.
Brandywine
A seedless male tree that blazes brilliant scarlet in fall before deepening into a rich reddish purple.
Red Rocket
A slim column of a tree, around 40 feet (12 m) tall and just about 15 feet (5 m) wide, ready-made for tight spots.
How to propagate
Red maple sprouts from seed with almost no effort, though seedlings keep you guessing on fall color. To lock in a cultivar's exact traits, growers reach for cuttings or grafting.
SeedEasy
Sow fresh samaras in late spring to early summer as they ripen; some seed lots benefit from cold stratification. · 1 to 2 growing seasons
Seed is the fun, easy way in. Sow the winged samaras fresh in late spring to early summer as they drop, give any stubborn lots a cold-stratification chill, and let them dig in over one to two growing seasons. Just remember seedlings vary, especially in fall color, so a named cultivar will not come true from them.
Stem cuttingsModerate
Take softwood cuttings in early summer. · Several weeks to root, then a season or more to establish.
Softwood cuttings are worth a shot, even if they run hot and cold. Take them in early summer, expect several weeks for roots to fire up, and count on a season or more before the young tree really settles.
GraftingDemanding
Bench graft or bud in the dormant or growing season onto seedling rootstock. · 1 or more seasons
Grafting is how nurseries keep a cultivar true, since it never comes true from seed. Bench graft or bud onto seedling rootstock in the dormant or growing season, then give it a season or more for the union to take and grow on. It is demanding work that rewards experienced hands.
Myths
Red maple is risky to grow near cats and dogs.
The ASPCA rates it non-toxic to both. The serious, sometimes fatal danger targets horses that eat wilted or dried leaves, so a home with cats or dogs can grow this tree with zero worry.
Only red maple's seeds or bark can hurt horses.
The toxin loads into the leaves, not the seeds or bark. Wilted or dried fallen leaves are the most dangerous form going, while fresh green leaves on the tree pose far less of a threat.