Aesculus carnea Briotii / Red Horse Chestnut

Common Name: Red Horse Chestnut, Briotii Horse Chestnut

Botanical Name: Aesculus × carnea ‘Briotii’

Family: Sapindaceae

Origin: Garden hybrid (cross between A. hippocastanum and A. pavia)

Mature Height: 15-20 metres

Mature Spread: 10-15 metres

Growth Rate: Moderate (30-40cm per year)

Foliage: Deciduous; large, palmate leaves with 5-7 leaflets, dark green through summer, turning yellow-bronze in autumn

Flowers: Spectacular upright panicles (20-25cm) of deep rose-red to coral-pink flowers in May-June; showy and abundant

Fruit: Smooth or slightly spiny conkers (less abundant than common horse chestnut)

Soil Requirements: Adaptable; prefers moist, well-drained, fertile soil; tolerates clay and loam; avoid waterlogged or very dry conditions

Light Requirements: Full sun to partial shade

Hardiness: Fully hardy (USDA Zone 4-8); tolerates urban pollution and exposed sites

Special Features: Outstanding floral display; excellent shade tree; attractive to pollinators; architectural form; less prone to leaf miner than common horse chestnut

The Red Horse Chestnut ‘Briotii’ is spring’s showstopper – a tree that announces the season’s arrival with an extravagant display of deep rose-red flower spires that glow against fresh green foliage. This is one of the finest cultivars of Aesculus × carnea, selected for its particularly rich flower colour and vigorous, symmetrical growth.

In late spring, the tree becomes a beacon of colour as hundreds of upright flower panicles emerge, each one a perfect pyramid of rose-red blooms marked with subtle yellow throats. Bees and other pollinators work the flowers with devotion, adding movement and life to the spectacle. The display lasts for several weeks, transforming the tree into a living sculpture that draws the eye from across the garden.

The foliage is equally impressive – large, hand-shaped leaves composed of five to seven leaflets create a bold, architectural canopy that provides deep, cooling shade through the summer months. The leaves emerge with a bronze tint before maturing to rich green, then turning warm yellow-bronze tones in autumn before falling.

Unlike its parent Aesculus hippocastanum, ‘Briotii’ produces fewer conkers, making it tidier in formal settings whilst still offering the occasional glossy brown treasure for children to collect. The tree’s naturally rounded, symmetrical crown requires little pruning to maintain its elegant form.

What sets ‘Briotii’ apart from the common horse chestnut is its superior resistance to horse chestnut leaf miner – the pest that causes unsightly browning on standard horse chestnuts. Whilst not immune, ‘Briotii’ shows notably better tolerance, maintaining cleaner, healthier foliage through the season.

This is a tree for generous spaces – avenues, parkland, large gardens, and estate settings where its full majesty can be appreciated. It’s a tree that creates memories, marks occasions, and becomes a beloved landmark in the landscape.

Choose a location with ample space for the mature canopy – at least 12-15 metres from buildings, boundaries, and other large trees. The site should receive full sun or light partial shade, with moist, fertile, well-drained soil. ‘Briotii’ tolerates clay and loam but dislikes waterlogged or very dry, sandy conditions.

Dig a generous planting hole at least twice the width of the root ball but no deeper. Position the tree so the root flare (where the trunk widens at the base) sits just above soil level. Backfill with excavated soil enriched with well-rotted compost or manure, firm gently, and water thoroughly. Stake young trees for the first 2-3 years using a single angled stake and flexible tree tie.

Apply a 7-10cm layer of organic mulch around the base, extending to the drip line but keeping it clear of the trunk.

Plant bare-root or root-balled specimens from November to March, or container-grown trees year-round (though autumn planting is ideal for establishment).

Water deeply and regularly during the first two growing seasons, particularly during dry spells. Young trees require consistent moisture to establish strong root systems. Once established, ‘Briotii’ is reasonably drought-tolerant but performs best with occasional deep watering during prolonged dry periods.

Feed young trees each spring with a balanced slow-release fertiliser or a generous top-dressing of well-rotted manure or compost. Mature specimens require minimal feeding – simply maintain the mulch layer to conserve moisture and add organic matter.

The Red Horse Chestnut requires minimal pruning and naturally develops a well-balanced crown. Remove any dead, damaged, diseased, or crossing branches in late winter (January-February) when the tree is fully dormant and the structure is clearly visible.

Avoid heavy pruning, as horse chestnuts do not respond well to hard cuts and may be slow to heal. If formative pruning is needed, do so gradually over several years whilst the tree is young.

Remove any suckers that appear at the base promptly. Check and adjust tree ties regularly to prevent rubbing or constriction as the trunk expands.

Winter: Bold architectural branch structure; large, sticky buds swell dramatically from February onwards, signalling spring’s approach.

Spring: Fresh green leaves unfurl in April; spectacular rose-red flower panicles appear in May-June, creating a breathtaking display.

Summer: Dense, cooling canopy of dark green palmate foliage; smooth or lightly spiny conkers begin to develop.

Autumn: Foliage turns warm yellow-bronze; glossy brown conkers fall (though less abundantly than common horse chestnut).

The Red Horse Chestnut’s bold presence is best complemented by understated companions that won’t compete for attention during its flowering season. Underplant with shade-tolerant perennials such as Geranium macrorrhizum, Alchemilla mollis, Hosta, or ferns once the canopy matures.

Spring bulbs – Narcissus, Crocus, and Anemone blanda – can be naturalised beneath the canopy to provide early colour before the tree leafs out fully.

For avenue planting, space trees 12-15 metres apart to allow each specimen to develop its full, symmetrical form.

Generally robust. May be affected by horse chestnut leaf miner (causes browning of leaves from midsummer), though ‘Briotii’ shows better resistance than common horse chestnut. Occasionally susceptible to coral spot fungus on dead wood (remove promptly) or powdery mildew in dry conditions (usually cosmetic only).

Bleeding canker (Pseudomonas syringae) can affect horse chestnuts – watch for dark, weeping patches on the bark and consult an arborist if symptoms appear.

Our Red Horse Chestnuts are carefully grown to ensure strong, well-structured specimens with healthy root systems. Whether you’re planting a grand avenue, creating a focal point in a generous garden, or establishing a tree that will be admired for generations, ‘Briotii’ offers unmatched floral drama, architectural presence, and enduring beauty. This is a tree that makes a statement – and keeps its promise for decades to come.