The horse Chestnut was the tree that Anne Frank mentioned in her diary. While the original tree fell down in 2010, there have been new trees planted around the world from the original seeds. Horse Chestnut ‘s seeds resemble chestnuts, but they are inedible and toxic.
I. Appearance and Characteristics
Aesculus hippocastanum, the horse chestnut, is a species of flowering plant in the maple, soapberry and lychee family Sapindaceae. It is a large, deciduous, synoecious (hermaphroditic-flowered) tree. It is also called horse-chestnut, European horsechestnut, buckeye, and conker tree. It is not to be confused with the Spanish chestnut, Castanea sativa, which is a tree in another family, Fagaceae.
The common name horse chestnut originates from the similarity of the leaves and fruits to sweet chestnuts, Castanea sativa (a tree in a different family, the Fagaceae), together with the alleged observation that the fruit or seeds could help panting or coughing horses.
Although it is sometimes known as buckeye, for the resemblance of the seed to a deer’s eye, the term buckeye is more commonly used for New World members of the genus Aesculus.
Aesculus hippocastanum is a large tree, growing to about 39 meters (128 ft) tall with a domed crown of stout branches. On old trees, the outer branches are often pendulous with curled-up tips. The leaves are opposite and palmately compound, with 5–7 leaflets 13–30 cm (5–12 in) long, making the whole leaf up to 60 cm (24 in) across, with a 7–20 cm (3–8 in) petiole. The leaf scars left on twigs after the leaves have fallen have a distinctive horseshoe shape, complete with seven “nails”.
The flowers are usually white with a yellow to pink blotch at the base of the petals; they are produced in spring in erect panicles 10–30 cm (4–12 in) tall with about 20–50 flowers on each panicle. Its pollen is not poisonous for honey bees. Usually only 1–5 fruits develop on each panicle. The shell is a green, spiky capsule containing one (rarely two or three) nut-like seeds called conkers or horse-chestnuts. Each conker is 2–4 cm (3⁄4–1+1⁄2 in) in diameter, glossy nut-brown with a whitish scar at the base.
II. How to Grow and Care
Sunlight
Horse Chestnut requires sunlight to grow. It can grow in partial shade to full sun. A position facing the sun is the most preferred, especially in the seedling stage, when sufficient sunlight is essential. In the shade, these plants are usually thin and prone to disease.
In hot summers, be wary of direct sunlight burning the plants. To avoid sunburn, put up shade nets for young trees. Large trees can be protected by painting their trunks white in late fall or early summer, or by covering the base of the trunk with organic mulch.
Watering
Horse chestnut will grow best when soil is kept moist. In fact, it won’t tolerate dry conditions well. When establishing a new tree, water it well after you plant it and continue to water weekly through the summer.
Temperature
Horse Chestnut prefers a moist growing environment with a temperature of 12 to 25 ℃. It can tolerate a low temperature of -40 ℃. Above 30 ℃, growth slows, and its leaves and trunk are sensitive to damage from high heat.
Soil
Horse Chestnut roots are deep and extensive, so its planting location requires a deep soil layer. It grows well in fertile, well-drained, slightly acidic to neutral (pH 5.5-7) sandy soil. Although it can also grow in light saline soil, its growth won’t be as good.
Fertilizing
Fertilize the horse chestnut regularly as it becomes established. You can use liquid, granular, stakes, or organic manure. Follow package directions. Once established, fertilize the tree annually in the spring.
Planting Instructions
It’s best to transplant one-year-old seedlings in spring. When transplanting, dig deep pits and apply base fertilizer. Since horse Chestnut has a taproot system and there are few fibrous roots, root balls must be transplanted whole to minimize root damage. If subsequent transplanting is planned, maintain a distance of about 1.5 m between small trees; if the position is fixed and the trees won’t be moved, maintain a distance of at least 4 m. Keep the soil moist after planting small trees to prevent the buds from drying up.
If you buy a large sapling that has been growing for several years, prune some branches before transplanting to reduce water evaporation and keep the sapling hydrated. You can prune overgrown, diseased, or damaged branches to about one-third of the original branches of the canopy.
In addition, remove some of the leaves to reduce water evaporation. Large saplings need to be transplanted with soil. The size of the root ball is generally 7-10 times the diameter of the seedling at breast height. Dig a pit 50 to 60 cm deep, and keep trees at least 4 m apart. After planting, compact and water the soil thoroughly.
Pruning
Most trees benefit from some pruning to give the tre its best shape. If you prune horse chestnut, do it in the early spring or in the fall once leaves have fallen. Remove those branches that are low or crowded.
Propagation
Propagating a tree requires a lot of patience and time. You can take 4-6 in. cuttings of new wood in the spring or cuttings of hard wood in the fall. Dip the cut end in rooting hormone and place cuttings in a container with soil. If you attempt propagation in the fall, protect the cuttings from freezing. Keep them indoors for protection, yet keep them cool. But if you try and don’t have success, visit your local nursery. It is a sure-fire way to add this tree to your landscape.
Pests and Diseases
Common Pests & Plant Diseases
Two fungi can bother common horse chestnut: leaf blotch and anthracnose. You’ll see leaf blotch on leaves. It presents with reddish-brown spots surrounded with yellow. The infected leaves might curl. To minimize the issue for future growing seasons, rake and dispose of fallen leaves away from your property. Anthracnose presents earlier in the season on new growth wood and leaves. To treat, prune to remove infected twigs.
Pests that bother horse chestnut include Japanese beetles and white-marked tussock moths. To control, spray for the moth’s caterpillar and beetles. Additionally, you can set Japanese beetle traps away from the tree to lure the beatles from the tree. The trap will work to reduce the number of beetles but won’t eradicate them.
Common Problems
The tree can also have problems with drought, resulting in scorched leaves. To prevent, make sure the tree has regular water while becoming established and during exceptionally dry seasons.
III. Uses and Benefits
- Ornamental uses
Horse Chestnut (Aesculus hippocastanum) is a large tree with a wide-spreading canopy that is only suitable for larger gardens and landscapes due to the amount of space it takes up. Still, it’s an attractive tree that produces plentiful spring flowers and large brown nuts. Its wide crown makes it a good shade or specimen tree for lawns and parks. Unfortunately, few plants pair well with horse Chestnut due to its allelopathic nature.
- Medicinal uses
The seed extract standardized to around 20 percent aescin (escin) is possibly useful in traditional medicine for its effect on venous tone. A Cochrane Review suggested that horse chestnut seed extract may be an efficacious and safe short-term treatment for chronic venous insufficiency, but definitive randomized controlled trials had not been conducted to confirm the efficacy.
IV. Types of Horse Chestnut
Aesculus X Arnoldiana ‘Autumn Splendor grows in Zones 6-8 (USDA), in US, MS, and LS. An attractive hybrid of Aesculus flava, Aesculus pavia, and Aesculus glabra. Grows to 35-40 ft. tall and nearly as wide. Glossy, dark green leaves with five (rarely seven) leaflets turn brilliant maroon in autumn and are resistant to leaf scorch. Yellow flowers, each with an orange-red blotch, are borne in clusters to 8 inches long. Best with some shade.
Aesculus X Carnea grows in Zones 6-8 (USDA), in US, MS, and LS. It grows to 40 ft tall and 30 ft wide. Round headed with large, dark green leaves, each divided into five leaflets; casts dense shade. Bears hundreds of 8 inches-long plumes of soft pink to red flowers. Briotii has rosy crimson flowers; ‘Fort McNair’ blooms rose-pink, and ‘O’Neil’s Red’ has bright red blooms.
Aesculus Flava(Aesculus Octandra) also known as Yellow Buckeye, or Sweet Buckeye, grows in Zones 6-8 (USDA), in US, MS, and LS. Native to the American South. Most majestic of the North American native species: handsome, round-crowned tree to 90 ft. tall and 50 ft. wide, with dark green leaves divided into five to seven finely toothed, 5- to 8 inch-long leaflets. Yellow flowers form on erect panicles; less showy than those of Aesculus hippocastanum. Smooth, brown bark and orange fall foliage.
Aesculus Glabra, also known as Ohio Buckeye, grows in Zone 6-7 (USDA), in US and MS. From the central and eastern U.S. Low-branching tree with dense, rounded form; to 40 ft. or possibly taller, to 30 ft. wide. Early to leaf out. Foliage is bright green when new, matures to dark green, turns yellow to orange in fall. Greenish yellow flowers in 4- to 7-inch clusters. Prickly seed capsules enclose shiny brown buckeyes.
Aesculus G, also known as Texas Buckeye, grows in Zone 6-8 (USDA), in US, MS, and LS. Attractive small tree to 15-20 ft. or taller, 12-15 ft. wide. Leaves are divided into seven to nine narrow, pointed, 3- to 5 inches-long leaflets. Pale yellow flowers in late spring. Weight of fruit may bend branches in fall.
Aesculus Parviflora, or Bottlebrush Buckeye, grows in Zone 6-9 (USDA), in US, MS, CS, and LS. Native to southeastern U.S. Shrub to 12-15 ft. tall and wide, spreading by suckers, with dark green leaves divided into five to seven 3- to 8-inch leaflets. Very showy white flower clusters (812 inches tall, 24 inches wide). Bright yellow fall foliage. Good choice for massing, shrub borders, or specimen or understory planting.
Aesculus Pavia, or Red Buckeye, grows in Zone 6-9 (USDA), in US, MS, LS, and CS. Native to eastern U.S. Understory shrub or tree grows to 12-20 ft. tall and as wide, with irregular rounded crown. Glossy deep green leaves with five to seven 3- to 6 inches-long leaflets. Bears narrow, erect 10 inch clusters of bright red or orange-red (rarely yellow) flowers. Does best in light shade. Good choice for warm, humid climates.
Find Where to Buy the Best Horse Chestnut (Aesculus hippocastanum)
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