In wet, boggy spots where few trees will grow, silver maple (Acer saccharinum) saves the day. It deserves ground cover plants to complement its majestic, graceful style. This North American woodland tree bears a crown of leaves with silvery undersides, and grows 50 to 80 feet tall and 35 to 70 feet wide. Ground cover plants suitable for growing beneath silver maple must be hardy within its U.S. Department of Agriculture plant hardiness range 3 through 9 and tolerate the shady, moist conditions around its roots.
Vigorous, spreading plants provide effective ground cover in the difficult conditions beneath silver maples. When growing in moist soil and shady conditions foam flower (Tiarella cordifolia) spreads rapidly through runners. This herbaceous perennial grows 9 to 12 inches tall and bears pink or white spring flowers on erect stems above heart-shaped leaves. Variegated common periwinkle (Vinca minor "Variegata") is another shade-tolerant plant known to spread vigorously. Bearing a profuse display of lilac blue spring blooms and dark green and cream, evergreen foliage, it grows 6 to 8 inches tall. Both plants are suitable for USDA zones 4 through 9.
Low-growing, shade-tolerant plants carpet the ground beneath silver maples, replacing turf in areas where grass grows sparsely. Loosestrife (Lysimachia japonica var. minutissima) grows 3 inches tall and bears star-shaped yellow summer flowers that cover its tiny oval-leaved foliage. Loosestrife is hardy in USDA zones 5 through 8 and stays evergreen in warm climates. Woodland white violet (Viola blanda) grows 1 to 5 inches tall and bears fragrant white and purple-veined spring flowers. This herbaceous perennial is hardy in USDA zones 2 through 7. Both plants grow well in the moist soils the silver maple prefers.
When silver maple leaves fall, evergreen ground cover shrubs and ferns provide color through winter. Creeping mahonia (Mahonia repens) leaves are evergreen and spiny, and it bears bright yellow spring flowers followed by blue-black berries. This shrub is suitable for moist, shady sites and is hardy in USDA zones 5 through 8. It grows 18 to 24 inches tall and 36 to 48 inches wide. A plant that tolerates similar conditions is holly fern (Cyrtomium falcatum "Rochfordianum"). Hardy in USDA zones 6 through 10, this plant bears attractive fronds of glossy dark green leaves and grows 24 to 36 inches tall and 18 inches wide.
Planting and Care
Silver maple tolerates planting around its roots, but gardeners can increase their chances of success by taking care not to damage tree roots and by providing aftercare for plants. Dig planting holes just large enough to accommodate plant rootballs, and avoid cutting through any roots thicker than 1 1/2 to 2 inches. After firming plants into the ground, water thoroughly and continue to water regularly throughout the first year to help plants establish. Spray a ready-mixed, general purpose foliar fertilizer on the leaves of the ground-cover plants.