Tree · Sapindaceae
Sugar Maple
Acer saccharum
Rooted in deep, moist soil with room to spread, the sugar maple raises a broad crown of leaves that catch fire in fall.
Full sun
Every 7–14 days
USDA 3–8
39–79 ft · 12–24 m
Overview
The sugar maple grows into a broad, rounded shade tree, its heavy trunk rising into a dense canopy of green leaves that can top 80 feet (24 m). Through summer that packed crown throws deep, cool shade over the ground below. When autumn turns, every leaf ignites in orange, red, and gold, a blaze of color that is the sight most people know this tree by.
In April the branches carry small, inconspicuous greenish-yellow flowers that open just before or alongside the new leaves, an easy detail to miss against the swelling buds. This is a tree of cold country, hardy across zones 3 through 8 and unbothered by winters that sink to -40°F (-40°C). Heat, road salt, and the packed soil of a tight lot leave their marks on it, so it wants deep, fertile, evenly moist ground with open room for its roots.
Every inch comes slowly. Sugar maple builds its frame at a patient pace and lives for generations, so the young tree you set out is a shape that fills in over decades. In late winter the clear sap inside the wood runs sweet, and sugarhouses across the north tap that flow each spring to boil it down into maple syrup.
Care
The short version: give the sugar maple full sun to part shade, deep, fertile, evenly moist but well-drained soil, about an inch of water a week through heat and drought, and a spot well clear of pavement and road salt.
Light
Sugar maple colors and fills out best in full sun and still takes partial shade in stride, especially while young. More light feeds richer fall color and a thicker, fuller crown, though a half-day of sun raises a healthy tree.
Water
The soil stays deep and evenly moist, with a watering roughly every 7 to 14 days when the rain falls short. Through real heat or drought, an established tree drinks about an inch of water a week, which keeps the leaf edges from browning into scorch.
Soil
The roots want deep, fertile loam that stays moist yet drains freely and runs dark with organic matter. A pH from 5.5 to 7.0, slightly acidic to neutral, suits them, and they will not settle into compacted, soggy ground.
Temperature
This is a cold-hardy tree through and through, at ease from -40°F to 95°F (-40°C to 35°C). It thrives in the north and labors where summers stretch long and hot.
Humidity
Plain outdoor air is all it asks, so there is no humidity mark to hit. Open airflow and steady soil moisture do far more for the leaves than any dampness in the air.
Feeding
Feeding falls in early spring with a balanced slow-release tree fertilizer, and a soil test sets how much the tree truly needs. A ring of mulch laid around the drip line breaks down slowly to feed the roots.
Pruning
Cutting belongs to summer or full dormancy, when dead, damaged, or crossing limbs come off, because a maple pruned in late winter or early spring bleeds sap heavily from the wound. Wipe the blade between cuts with 10 percent bleach or 70 percent alcohol so no disease rides from limb to limb.
Repotting
Sugar maple is a landscape tree, not a container plant, so repotting rarely comes up. On nursery or potted stock, watch for roots circling the trunk flare or a top that lags a crowded root ball, and ease those roots loose before planting.
Size & spacing
This tree spreads its frame wide. It stands 40 to 80 feet (12 to 24 m) tall and reaches 30 to 60 feet (9 to 18 m) across, so its place sits well clear of houses, drives, and power lines.
When to plant
Sugar maple goes into the ground in spring or fall, while the weather is cool and the roots can knit in before stress arrives. The small greenish-yellow flowers open in April, just before or with the unfurling leaves, and the true spectacle waits for autumn, when the whole canopy deepens into red, orange, and gold.
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: Inconspicuous greenish-yellow flowers in April before or with the leaves; brilliant red, orange, and yellow fall color
Hardiness
USDA hardiness zones: 3–8
Temperature: down to -40°C
Troubleshooting
Most sugar maple trouble writes itself on the leaves first, whether the cause is heat, a soil fungus, or a soaking spring. Learn the look of each mark and you can tell a surface blemish from a threat to the whole tree. Match what you see below before reaching for a sprayer.
One flank yellowing and going limp against a healthy crown
A single limb or one whole side yellowing, drooping, and dying while the opposite crown stays green is the tell of Verticillium wilt, a soil fungus that clogs the water-carrying wood from the inside. Pare a curl of bark from a wilting branch and the sapwood beneath shows green or brown streaks running through the pale grain, though only a lab test names it for certain, since most maple diseases wear the same face. No cure exists, so dead wood comes out as it browns, and steady water and feeding carry the tree through its remaining years.
Fix:
- There is no cure; prune out dead branches as they appear
- Water about one inch per week and fertilize based on a soil test to prolong tree life
- Mulch around the drip line and sanitize pruning tools with 10 percent bleach or 70 percent alcohol between cuts
Tan dead patches between the veins in dry heat
Pale tan and brown blotches spreading along the leaf rims and into the panels between the veins during a hot, dry spell are the mark of leaf scorch. The roots fall behind on water and the leaf tissue dries and dies at its thirstiest edges. Salty soil, packed ground, and a cramped root zone beside pavement deepen the browning. About an inch of water a week through heat and drought, plus a blanket of mulch over the roots, keeps the leaves whole.
Fix:
- Water established trees with about one inch of irrigation per week during heat and drought
- Mulch over the root zone to conserve moisture and moderate soil temperature
- Avoid salt accumulation and soil contaminants around the roots
Raised lacquer-black dots inside yellow rings in late summer
Those raised, glassy black dots sitting inside soft yellow rings on the upper leaf surface are tar spot, a leaf fungus whose dramatic look far outruns the slight harm it does. The black crusts ride out winter on the fallen leaves, so gathering and destroying that litter each autumn cuts the cycle short. A copper fungicide at leaf-out can clear a small tree, yet on most maples the shine simply is not worth chasing.
Fix:
- Rake up and destroy fallen leaves where the fungus overwinters
- If desired on small trees, apply a copper-based fungicide, mancozeb, or triadimefon three times at two-week intervals starting at spring leaf unfurl
Vein-following brown blotches and dead buds after a wet spring
A long, cool, soaking spring calls up anthracnose, a fungus that stains the leaves brown along the lines of their veins, blackens the buds, and knots the twigs into crooked dieback. The infected leaves carry the spores, so raking and destroying them clears the threat. Open airflow and quick-drying foliage keep the fungus from settling in at all.
Fix:
- Rake and destroy fallen infected leaves
- On valuable small trees, spray a copper-based fungicide, mancozeb, or chlorothalonil three times at two-week intervals from spring leaf emergence
Toxicity
The news is reassuring on every count. Sugar maple is safe for people, pets, and livestock alike, and its boiled-down sap is the very syrup poured over pancakes. The wilted-leaf poisoning that worries horse owners comes from red and silver maple, not from this tree.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats are safe. A cat that bats at and chews a fallen leaf meets nothing harmful in the tissue.
Dogs None
Dogs are unharmed. The broad leaves, the bark, and the slender twigs carry nothing that troubles them.
Horses None
Sugar maple is safe for horses. The red-blood-cell poisoning traces to the wilted leaves of red maple and silver maple, not to this species.
Rabbits None
Rabbits can browse the green foliage without harm.
Livestock None
Cattle, goats, and sheep graze beneath sugar maples with no ill effect.
Birds None
Birds nest and feed safely within the dense canopy, and the winged seeds feed plenty of wildlife.
People None
People are safe with it. The clear sap, boiled down, becomes maple syrup, so part of this tree reaches the breakfast table.
Non-toxic to cats and dogs. Note that it is the related red maple (Acer rubrum) whose wilted leaves are notoriously toxic to horses; sugar maple is not the species classically implicated, but as a general precaution wilted maple leaves of any species are best kept away from horses.
Varieties
Most sugar maples sold for the yard are named cultivars chosen for tougher leaves and brighter fall color. These are the ones worth asking for by name.
Green Mountain
A heat- and drought-tolerant selection that carries a tight, dense oval crown and burns orange-red in fall.
Legacy
A vigorous, scorch-resistant cultivar clad in thick, glossy leaves that hold up against tearing and drought.
Fall Fiesta
A tough, fast-establishing tree that colors a dependable yellow-orange to red in autumn on leaves that cling on late.
How to propagate
Sugar maple grows from seed with a stretch of cold treatment, though the named selections hold their character only when grafted.
SeedModerate
Sow outdoors in fall or after 60-90 days of cold, moist stratification before spring sowing · 1 to 2 growing seasons
Sugar maple seed stays dormant until cold breaks its rest, so it goes into the ground outdoors in fall or gets 60 to 90 days of cold, moist stratification before a spring sowing. The young seedling roots down and fills out over 1 to 2 growing seasons. Layering and stem cuttings will also raise the species.
GraftingDemanding
Late winter (bench graft) or summer (budding) · 1 to 2 seasons
Named selections like Green Mountain and Legacy will not come true from seed, so growers graft or bud them onto seedling rootstock. Bench grafting is set in late winter and budding in summer, and the joined tissue knits over 1 to 2 seasons. The delicate union takes a steady hand, which places this among the demanding methods.
Myths
All maples, sugar maple included, are deadly poisonous to horses.
The danger belongs to red maple and silver maple, whose wilted leaves can shatter a horse's red blood cells. Sugar maple is not the culprit, and far from being poisonous, it is the very tree tapped for maple syrup.