Harbison's Hawthorn

Size, growth and what to expect

New grafts can grow a foot in a few months, but our growth estimator treats it as a medium grower, about a foot and a half a year. It is a shrub or small tree of 10 to 26 feet, usually with two or three stems. Wild plants old enough to flower stood 10 to 19 feet tall.

Clusters of five to twelve white flowers, each three quarters of an inch to an inch across, open in early May. The haws ripen orange-red to red from September into November, downy and about half an inch to nearly an inch across. Animals eat the fallen fruit.

Its home is dry, rocky woods over limestone, where rusty blackhaw, flowering dogwood and redbud grow with it. In west Tennessee it grows scattered over about 74 acres of forest, young woods and pasture. Older records from Alabama, Georgia and Mississippi rest on a broader view of the species, one that took in its close relative Ashe's hawthorn.

How to grow Harbison's Hawthorn

Harbison's hawthorn wants full sun or light shade, because plants shaded by taller trees grow weakly and bloom little. In the wild it grows on dry, rocky ground over limestone and on silty soils, so give it a well-drained site. Its stout thorns grow up to an inch and a half long, so keep it back from paths. Set trees 20 feet apart, and keep each one 15 feet from a wall and 15 feet from overhead wires.

Saplings ship bare-root or potted. Plant them dormant, from leaf fall until bud swell, in a hole wider than the roots and no deeper. Set the root flare at the soil line, put the native soil back in, and keep the mulch clear of the trunk. Soften the fruit in a warm, damp bag for up to a week, then rub the seed clean. Chill the seed damp in the refrigerator for about four months, and sow it in spring. In trials only a fifth to a quarter of the seed sprouted, so sow plenty.

Water weekly through the first summer, and in dry spells for the next two. Deer browse hawthorn leaves and twigs and rabbits gnaw young bark, so cage each sapling for its first three years. Keep taller trees and brush from shading it, since wild plants freed from shade flowered and fruited more.

Harbison's hawthorn has four sets of chromosomes, and hawthorns like it usually set seed with their own pollen, so one tree can bear alone. Some of its seed is thought to form without fertilization, so a seedling can be a near copy of its mother. Like other hawthorns it can suffer from fungal and bacterial diseases and insect pests. One rust spends part of its life on eastern redcedar, which is common where it grows wild.