View a magnolia flower and you'll likely never forget its beauty or fragrance. If you have a garden spot that is plagued by flooding or occasionally wet soils after every thunderstorm, three magnolia species may prove useful. Make sure your soil is acidic and your winter climate matches the needs for survival on each type. Choose varieties that mature to an appropriate size, too.
Soggy acidic soils that often have shallow flooding after rain make good sites for the sweetbay magnolia (Magnolia virginiana). Even along the edges of a shallow pond, the sweetbay magnolia will flourish. Sometimes a large shrub but usually a small tree maturing to 20 to 30 feet and canopy width of 10 to 18 feet, the sweetbay magnolia's large leaves bear silvery green undersides that flash in the breeze. In late spring and early summer, branch tips bear rose- or lemon-scented white flowers that fade to tan-yellow with age. In cold winter regions the leaves fully drop away in autumn. Grow this tree, also called the swamp magnolia, in USDA Hardiness Zones 6 through 9.
A large park or shade tree, the cucumber tree (Magnolia acuminata) tolerates very moist soils that drain; therefore it is best just upland from the flooding low spots in a landscape. As long as this tree's roots never go underwater, it prospers in moist locations. Greenish yellow flowers occur in summer, but this tree is so-named because of the warty, green upright seed cones that follow. The foliage in autumn becomes a nice yellow before dropping. At maturity cucumber trees tower about 70 feet tall and 30 feet wide. The natural variety subcordata, the yellow cucumber tree, grows only 25 feet tall and 20 feet wide, making it a better choice for most garden landscapes in USDA Zones 4 through 8.
Much like the cucumber tree, the southern magnolia (Magnolia grandiflora) tolerates moist to occasionally wet soils that eventually drain away after rains. Southern magnolia remains evergreen with its large glossy green leaves with fuzzy brown undersides and large fragrant white flowers in spring and summer. It is a tree that demonstrates amazing tolerance of drought, too. The wild species becomes large at 60 to 80 feet tall and 50 feet wide. Consider choosing smaller-sized varieties such as 'Little Gem', 'D.D. Blanchard' and 'Bracken's Brown Beauty'. Overly wet soils retard the tree's growth habit and mature size across the growing range of USDA Zones 6 though 9.