The Horse Chestnut is part of a genus of 15 species of deciduous trees and shrubs. The Horse Chestnut originates from the Balkans but has now naturalised across much of Europe where it can reach heights of 25metres.
Horse Chestnut Spring Growth
Though easily grown from seed or collected, Horse Chestnuts are not commonly seen as bonsai due to their large palmate leaves that are up to 12 inches across, however root restriction and leaf-cutting will dramatically reduce them in size. The Horse Chestnut produces showy white flowers in early Summer (12 inches in height) followed by their infamous spiky green fruit in Autumn. There are now cultivors that have red and pink flowers that can also be used.
Bonsai cultivation notes
Position Full sun, out of strong winds.
Feeding Feed monthly with low nitrogen fertiliser to keep growth compact.
Repotting Must be kept pot-bound to keep growth compact, repot every 3 or 4 years in a basic soil mix.
Pruning Repeatedly prune back. Horse Chestnuts bud back easily and the resulting dense canopy will help reduce leaf-size. Remove individual leaflets to leave just 1 or 2 in place.
Defoliate in mid-summer to encourage a new crop of smaller leaves. As new sets of buds extend remove the apical bud to reduce internode length.
Wiring Relatively thick branches are still supple and can be bent, however, care should be taken as the bark is easily damaged by wire.
Propagation For best results sow seed (conkers) as soon as ripe outside.
Pests and diseases Canker, coral spot, leaf blight and scale insects.
Styles Best grown in a loose informal broom form in medium to extra-large sizes.