If you want flowering trees that generate white blooms in March, you have a few options. Your choices increase greatly if you can wait until April for such species to bloom. Landscaping trees with early spring flowers that are capable of handling the assorted climates the U.S. Department of Agriculture Plant Hardiness Zones throw at them attain different sizes and thus serve several functions.
USDA Zone 2 and Zone 3
USDA Zone 2 is too chilly for any trees to bear white flowers in March. In Zone 3, the American plum sometimes produces its white flowers late in March, if the weather cooperates. The flowers emerge before the foliage, making for an outstanding ornamental display. Hanging clusters of white flowers droop from the branches of European bird cherry during April. The tree grows to 40 feet and thrives in sunny areas. The cold-hardy Manchurian cherry tree blooms late in April. It flowers in Zone 2's warmer regions, producing its white flowers in clusters up to 24 inches long.
USDA Zone 4 and Zone 5
White March flowers on a downy serviceberry are a sign of spring in Zone 4 and Zone 5. The tree, at between 15 and 25 feet tall, grows well next to ponds or in shady woodland borders. Star magnolia is a deciduous Japanese species that grows to 20 feet and is used as a foundation plant. It blooms in March in these zones. April showers deliver white flowers on trees that include Juneberry, English hawthorn and many cultivars of flowering crabapples in both zones. Group the eastern redbud cultivar Royal White in groves and await its white flowers in April.
USDA Zone 6 and Zone 7
The goblet-shaped white flowers on a kobus magnolia bloom in March in Zone 6 and Zone 7 and have a pinkish tint. Kobus magnolia grows to 30 feet and is an ideal patio tree. Yulan, David's peach and yoshino cherry exhibit white March flowers in these warmer zones. April is the month for flowering dogwood cultivars such as "Cloud Nine" and "Cherokee Princess." The Carolina silverbell is an interesting specimen tree for lawns, growing to 35 feet. The drooping bell-like white flowers, in clusters of as many as five, bloom in April before or with the leaves.
USDA Zone 8, Zone 9 and Zone 10
In USDA Zone 8 and Zone 9, locate almond trees in sandy soil in full sun for the best results. The white March flowers are fragrant and yield edible nuts in the late autumn. White flowers with red splayed centers highlight the March branches of the tung-oil tree in all three zones. If you can find a jacktree at your local nursery, place it in well-draining acidic areas and take advantage of the white star-shaped flowers it features in April. Jacktree grows into Zone 10 from Zone 6, with yellow foliage giving it fall interest.