Gardening in eastern North America has many challenges. But it also has many glories. Among the latter are the two evergreen magnolia species that call the region home. Southern magnolia (Magnolia grandiflora) and evergreen forms of sweetbay magnolia (Magnolia virginiana var. australis) have it all: handsome gray bark; large, sweet-scented, creamy-white flowers in late spring (and sporadically until fall); and evergreen leaves that take center stage in winter.
These native beauties are also more cold-tolerant than most gardeners know. Although they hail from the Southeast United States, they succeed in cultivation into USDA Zone 5b. Centerpieces of many a Mid-Atlantic and Southeast garden, they’re also capable of making a statement in parts of New England, New York, and the Midwest.
Southern magnolia is one of those big, bold, primordial plants that looks like it just dropped in from the Cretaceous. Indeed, its ancestors dominated much of Earth’s vegetation some 70- to 90-million years ago, when dinosaurs roamed the planet. But this magnificent magnolia also works just fine as a visually dominant specimen tree for twenty-first-century landscapes.
In its boldest forms, Magnolia grandiflora takes the primordial look to awe-inspiring lengths (and breadths). The aptly named ‘Goliath’ (and the somewhat similar ‘Gloriosa’) produces enormous cupped flowers of ivory that open to a foot or more across, displayed against large, polished, relatively broad leaves. The flowers of ‘Samuel Sommer’ are even larger (to 14 inches across), and its leaves have striking rust-brown felting on their undersides. Selected for its abundance of bloom, ‘Majestic Beauty’ also features immense deep green leaves and a symmetrical, broadly conical growth habit. Cultivars ‘Angustifolia’ and ‘Lanceolata’ have narrower leaves, felted brown underneath.
Although typically forming a slow-growing, 40- to 60-foot tree, Southern magnolia sometimes assumes more compact forms, as in the narrowly conical, 30-foot-tall ‘Little Gem’. Its 4-inch-wide flowers are relatively precocious (most Southern magnolias varieties take several years to a decade to come to bloom), and as with most varieties, they recur sparingly after the main flush in late spring.
Two other compact Magnolia grandiflora cultivars are of particular interest to Northern gardeners. Both ‘Bracken’s Brown Beauty’ and ‘Edith Bogue’ have a good chance of succeeding into USDA Zone 5b in sites protected from winter sun and harsh northwest winds. For sheer hardiness and sturdiness, ‘Bracken’s Brown Beauty’ can’t be beat, although even this toughest of Southern magnolias will go brownish-tan in cold, Zone-6 winters. The slightly more delicate ‘Edith Bogue’ is notorious for losing limbs to heavy winter snow, and functions best in North gardens as an espalier, with her branches fixed to a stout frame (a shaded east-facing wall is ideal).
Whatever the climatic zone, Southern magnolia does best in relatively fertile soil that’s not too sandy or heavy. A good compost (such as Fafard Premium Natural & Organic Compost) can help bring marginal soils into line.
Native from Texas to North-Coastal Massachusetts, Magnolia virginiana makes a natural choice for gardens from USDA Zones 5 to 9. Evergreen forms of this elegant small tree – known botanically as variety australis – are confined to the Southeast, and tend to either expire or defoliate in Zone 5 and 6 winters. Exceptions do occur, however, including the cultivars ‘Henry Hicks’ and ‘Moonglow’, both of which are hardy and often evergreen (or semi-evergreen) into Zone 5b.
In all its forms, sweetbay magnolia is one of the finest small trees for American gardens. Typically single-trunked in warmer climes and multi-stemmed in chillier regions, it bears oval, rich green leaves with silvery undersides that shimmer in the breeze. The cupped, creamy (almost primrose yellow) flowers debut in late spring and continue sporadically throughout summer, casting a piquant, questing fragrance reminiscent of roses or lemons. Attractive clusters of red-fleshed fruits follow the blooms. Often found in wetlands in nature, Magnolia virginiana is well suited for moister areas of the landscape (and loathes dry, sandy soil).
Also well worth growing is the hybrid between sweetbay magnolia and umbrella magnolia (Magnolia tripetala), which combines the fragrant, summer-long blooms of the former with the bold, primordial, deciduous foliage of the latter. Its cultivar ‘Cairn Croft’ is sometimes available from specialty nurseries. Crosses between sweetbay and Southern magnolia have been developed and introduced by hybridizers, but offer no notable advantages over the parents. For year-round leafage and beauty, these two exceptional natives can’t be beat.