Photo: Plant Image Library, CC BY-SA 2.0 · Wikimedia Commons

Bigleaf Magnolia

Magnolia macrophylla

Also called large-leaved cucumber tree, greatleaf magnolia.

The largest simple leaves and flowers of any tree native to North America, with leaves up to 3 feet long and fragrant white flowers up to 14 inches across.

Showy flowersRareWildlife value

Type: Medium tree
Mature height: 30–40 ft
USDA zones: 5–9
Growth rate: Slow
Sun: Full, Part
Soil moisture: Average
Grows wild in: Rich moist slopes, the forest understory and floodplain forests
Native range: 15 states, north to New York and south and west to Louisiana
List all 15
Alabama, Arkansas, Georgia, Kentucky, Louisiana, Maryland, Mississippi, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia and West Virginia
Also recorded in 1 other state, outside its native range. See what is native in your state

Hardiness zones Find your zone by ZIP code

Bigleaf magnolia is a single-trunked tree of the southeastern United States, with leaves bright green above and silvery beneath. It is rarely found in the wild, where it grows in small, isolated stands. NatureServe ranks it secure overall but critically imperiled in Virginia, South Carolina and Arkansas, and Ohio lists it as endangered. Ashe's magnolia, which some botanists treat as its subspecies, is a smaller, often multi-trunked tree of the Florida panhandle that flowers when young. Bigleaf grows larger, with bigger leaves and more stamens, over a far wider range. Give it room in a sheltered lawn or at a woodland edge, where the huge leaves lend the garden a tropical look.

Size, growth and what to expect

Bigleaf magnolia grows slowly, about a foot a year in our growth estimator. It makes a tree of 30 to 40 feet with a crown as wide, and the largest known, in Kentucky, stood 105 feet. A seedling may take 12 or more years to flower.

The flowers open in May and June, creamy white with a purple blotch at the base of the inner petals. A round, rose-red cone 2 to 3 inches long follows and ripens in late summer. Its red seeds hang on threads, and birds and small mammals eat them.

It grows wild in scattered stands from Ohio and Kentucky south to Georgia and Louisiana, in alluvial woods, sheltered valleys and rich ravines. In Arkansas it is known from one site, where two trees were recorded in 1981 and a survey in 1995 found none.

How to grow Bigleaf Magnolia

Bigleaf magnolia grows best in part shade or full sun, in a rich, moist soil, acid to neutral, that drains well. It does poorly in dry or soggy ground and in city air. Wind shreds the huge leaves, so give it a sheltered spot. Plant it 20 feet from a wall, and set trees 30 feet apart. Keep it at least 15 feet from overhead wires.

Saplings ship potted. Magnolias grow thick, fleshy roots that heal slowly in cold soil, so plant at the end of winter or as the buds break in spring. Dig a hole wider than the root ball and no deeper. Set the root flare at the soil line, put the native soil back in, and keep the mulch clear of the trunk. Rub the red coat off the seed, and never let it dry. Sow it outdoors in fall, half an inch deep, under hardware cloth against mice. For spring, keep it damp in the refrigerator for at least 60 days first.

Water weekly through the first two summers and in long dry spells after that. Keep a wide ring of mulch over the roots. Deer and rabbits browse young magnolias, so guard the stem with wire for the first few years. Prune as little as possible, and only to take out dead or broken wood.

Bigleaf magnolia carries both male and female parts in each flower, and bees and beetles moving between its flowers can set seed on a lone tree. It has no serious pests or diseases. The flowers often open high in the crown, where they are hard to see up close. In fall the huge leaves drop and take some raking.

Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them.

Sources (13)