Culture
Easily grown in average, medium, well-drained soils in full sun to part shade. Prefers moist, fertile soils. Foliage tends to scorch and generally depreciate in dry conditions. This is a taprooted tree that once established is very difficult to transplant.
Noteworthy Characteristics
Aesculus hippocastanum, commonly called horsechestnut, is native to the Balkans. It is a medium to large deciduous tree that typically grows 50-75’ tall with an upright oval-rounded crown. Light green palmate compound leaves emerge in spring, each with 7 (less frequently 5) spreading ovate-oblong leaflets to 4-10” long. Leaves mature to dark green in summer. Fall color usually consists of undistinguished shades of yellow and brown. Showy white flowers with red or yellow markings appear in upright terminal panicles in mid-spring (May in St. Louis). Fruit is a globular dehiscent capsule consisting of 1-2 horsechestnut(s) encased by a leathery light brown husk covered with sharp spines. Fruit on the tree is interesting but not particularly ornamental. When ripe, each horsechestnut turns a handsome shiny dark mahogany brown with a round light tan scar. Chestnuts and horsechestnuts are in totally different families. Chestnuts (Castanea) are in the beech family (Fagaceae) and produce edible nuts. Horsechestnuts and buckeyes (Aesculus) are in the soapberry family (Sapindaceae) and produce poisonous nuts. Horsechestnut is closely related to Ohio buckeye, being most easily distinguished from the latter by having spiny sharp fruits and sticky buds.
Genus name is the Latin name for a kind of oak bearing edible acorns but applied by Linnaeus to this genus.
Specific epithet is the Latin name for horsechestnuts.
‘Baumannii’ is an old, double-flowered cultivar that was first identified in Geneva, Switzerland in 1819. It is primarily distinguished from the species by (1) later and longer bloom, (2) double white flowers, (3) no fruit and (4) taller and narrower habit.
Problems
Leaf blotch can be a significant problem. Powdery mildew and anthracnose are also frequent problems. Watch for bagworms, Japanese beetles and borers are infrequent but potentially troublesome. Leaf scorch (brown edges) may occur in droughty conditions or on sites exposed to wind.
Uses
A beautiful landscape tree for parks and large lawns. Depreciation of the foliage during the growing season due to disease, insect and scorching problems somewhat limits its value. It has been widely planted in the midwest as a street and shade tree.