A native broad leafed evergreen tree that does not hold up to frigid winters. Extreme low temperatures burn the leaves.
Flowers: small white blooms
Foliage: dark green dense leaves
Blooms: April to early May. American holly is dioecious, which means both a male and a female plant are needed for fruit production. Tiny creamy flowers of both sexes appear in late spring, with pollination occurring thanks to the visits of bees, wasps, ants, moths, and yellow jackets. A single male plant can pollinate up to three females.
Mature size: 20' — 30' tall and 10' — 20' wide. American holly grows somewhat slowly.
Hardy to zones: 5 — 6
Holly should be planted in fertile, moist, loose, acidic, well drained soil in partial to full sun. Ideal planting times are spring and fall up to before soil becomes frozen. Does poorly in shady conditions caused by surrounding trees. Give the holly its own root space without crowding. This holly grows in a pyramidal shape, but can be pruned.
Holly makes an excellent specimen plant or as a group planting. Typically, only female holly has the red berries.
American holly is prized as an easy-care tree for the home landscape. It normally doesn't need additional watering except when first planted, in severe droughts, or late fall before the ground freezes. Even well-established trees may need watering during a severe drought.
Over-fertilization should be avoided. Only one application of a slow-release granular fertilizer designed for acid-loving plants. Once or twice a year, give your holly a treat: an inch-deep mulch layer of used coffee grounds.
The tree requires routine pruning to keep it in shape. The American Holly is pyramidal shaped as young trees, then become more open and irregular as they mature. Prune to maintain a tighter shape. If necessary, an American holly that has completely lost its shape can be heavily pruned, removing branches at their point of origin. Some prune grouped hollies into hedges. When shaping these shrubs, especially for hedges, do not cut lower branches shorter than the higher branches. Hollies that are narrower at the bottom than the top often lose these lower branches due to lack of sun; sometimes the whole shrub dies.
December, when the plant is dormant, is the best time to prune holly. But it can be lightly pruned any time during the year. Heavy pruning after flowering or in summer reduces berry production.
Severe winter conditions, and sometimes soil deficiencies, may cause physiological problems such as sun scald and purple spot on the leaves of evergreen hollies. Winds blowing the spiny leaves together causes punctures in the foliage.
Spray holly leaves with anti-transpirant spray to protect surfaces from harsh winter sun and wind. Consider erecting a wind barrier of burlap or similar material (never use plastic!) around holly trees and shrubs exposed to prevailing winter winds. Spread winter mulch on the soil over the roots after the ground freezes.
Healthy American holly trees have few problems. If they do experience some stress, the insects that most often appear will be the leaf miner or scale. Leaf spot and mildew are two of the more common fungal diseases that will attack a stressed specimen.
The American Holly tree has been popular since the beginning of American history, having served Native Americans with wood for many different applications and berries that were used for buttons and barter. It was said to be a favorite of George Washington, and more than a dozen Hollies planted by him are still in evidence today. It is also widely known as the basic raw material for Christmas wreaths. The first scientific observation of the American Holly tree was recorded in 1744. (source: The Arbor Day Foundation)