Introduction

This hybrid of Aesculus hippocastanum and Aesculus pavia has very large, dark green leaves composed of five to seven leaflets, and will ultimately reach a height and spread of 35 to 50 feet but grows slowly. Although deciduous, ruby red horsechestnut does not produce any appreciable fall color and is well suited for use as a specimen. The tree is quite striking with dark green, coarse-textured foliage. Pyramidal in shape when very young, red horsechestnut develops slowly into a round, very dense shade tree by five to seven years of age, and is outstanding in the landscape for its beautiful springtime display of blossoms. The multitude of deep scarlet flowers in erect, 10-inch-long panicles at each branch tip are quite attractive to bees and hummingbirds. The prickly seedpods that can be messy on the original hybrid are nearly absent on this cultivar, making it better suited than the species for urban street tree planting.

General Information

Scientific name: Aesculus x carnea

Pronunciation: ESS-kew-lus x KAR-nee-uh

Common name(s): Ruby red horsechestnut

Family: Hippocastanaceae

USDA hardiness zones: 5A through 7B (Fig. 2)

Origin: not native to North America

Invasive potential: little invasive potential

Uses: street without sidewalk; sidewalk cutout (tree pit); tree lawn 3–4 feet wide; tree lawn 4–6 feet wide; tree lawn > 6 ft. wide; parking lot island 100–200 sq. ft.; parking lot island > 200 sq. ft.; specimen; shade; screen; highway median

Availability: somewhat available, may have to go out of the region to find the tree

Description

Height: 35 to 45 feet

Spread: 35 to 45 feet

Crown uniformity: symmetrical

Crown shape: pyramidal, round

Crown density: dense

Growth rate: slow

Texture: coarse

Foliage

Leaf arrangement: opposite/subopposite (Fig. 3)

Leaf type: palmately compound

Leaf margin: serrate

Leaf shape: oblanceolate

Leaf venation: pinnate

Leaf type and persistence: deciduous

Leaf blade length: 4 to 8 inches

Leaf color: green

Fall color: no color change

Fall characteristic: not showy

Flower

Flower color: pink, red

Flower characteristics: very showy

Fruit

Fruit shape: no fruit

Fruit length: no fruit

Fruit covering: no fruit

Fruit color: no fruit

Fruit characteristics: no fruit

Trunk and Branches

Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns

Pruning requirement: needed for strong structure

Breakage: resistant

Current year twig color: brown

Current year twig thickness: thick

Wood specific gravity: unknown

Culture

Light requirement: full sun

Soil tolerances: sand; loam; clay; acidic; well-drained

Drought tolerance: moderate

Aerosol salt tolerance: moderate

Other

Roots: not a problem

Winter interest: no

Outstanding tree: yes

Ozone sensitivity: unknown

Verticillium wilt susceptibility: resistant

Pest resistance: resistant to pests/diseases

Use and Management

Leaf and flower litter in the summer and fall may be objectionable to some people since the leaves are large and decompose slowly. Makes a great median street tree when provided with some irrigation during drought.

Ruby red horsechestnut will grow in full sun or light shade and prefers moist, well-drained, acid soils but grows in slightly alkaline soil. Plants are moderately tolerant to drought, wind, and salt, and resist the heat of the South very well. It holds up well in urban areas, even in restricted and compacted soil spaces. Red horsechestnut appears to be less susceptible to disease than either of the parents. Trunk bark may crack when exposed to the direct sun, so keep it shaded as much as possible by leaving lower branches on the tree and don't over-prune the tree, exposing the trunk suddenly to direct sun. The tree usually requires little pruning to develop a good form.

The cultivar 'Rosea' has pink flowers. 'O'Neil's Red' has double red flowers.

Pests and Diseases

No pests or diseases are of major concern, although this plant has not been thoroughly tested in the United States. Probably scorches less than Aesculus hippocastanum, and should be planted in its place.