American holly

Sun

Full sun to partial shade; denser growth and heavier fruiting usually occur in sun. Shelter from drying winter winds, especially near its cold limit.

Water

Moderate; keep the root zone evenly moist while establishing. Established trees tolerate short dry periods, but prolonged drought can cause leaf loss.

Soil

Moist, well-drained, acidic soil rich in organic matter. Avoid chalk, alkaline soil and sites that remain waterlogged.

Height

40-60 ft (12-18 m)

Spread

20-40 ft (6-12 m)

Flowers

Small, greenish-white flowers in late spring; male and female flowers usually occur on separate trees.

Foliage

Evergreen. Leathery, oval leaves with sharp marginal spines; generally dull dark green above and paler beneath.

Growth

Slow, commonly around 6-12 in (15-30 cm) a year once established.

Care needed

Low

• Plant in spring in cold regions, or autumn where winters are mild; keep the root flare at soil level.
• Water deeply during dry spells for the first two growing seasons, moistening the root ball and surrounding soil.
• Apply 2-3 in (5-8 cm) of organic mulch over the root zone, keeping it clear of the trunk.
• Test the soil before feeding; use a modest spring application of fertiliser for acid-loving plants only if growth or a soil test indicates a need.
• For berries, plant a known female with a male American holly that flowers at the same time nearby.
• Choose the permanent position carefully; established trees are difficult to transplant.

Pruning. Prune in late winter or early spring, removing dead, damaged or crossing branches and lightly shortening unwanted growth. Preserve the central leader and avoid topping; frequent clipping reduces flowers and berries.

Late winter

Remove damaged or crossing branches before new growth begins.

Spring

Plant in cold regions and check that the root flare remains above the mulch.

Late spring

Check that male and female trees flower together if reliable berry production is important.

Summer

Water young trees deeply during dry weather and inspect leaves for scale insects or leaf-miner damage.

Autumn

Plant in mild regions and replenish mulch without piling it against the trunk.

Winter

Water young trees during dry, frost-free periods if the soil is dry; leave berries for birds.

• Use as a long-lived specimen on a spacious lawn, allowing its lower branches to reach the ground.
• Plant a loose evergreen screen along a boundary where there is room for its mature width.
• Combine with rhododendrons, mountain laurels and ferns at an acidic woodland edge.
• Use its dark foliage as a backdrop to flowering dogwoods and other deciduous trees.
• Include female and male trees in a wildlife planting for flowers, fruit and year-round shelter.

Garden styles it suits: Traditional, Southern, Colonial Williamsburg, Woodland, Wildlife garden and Winter interest.

Plant it with: Flowering dogwood, Eastern redbud, Mountain laurel, Rhododendron, Christmas fern and Foamflower.

Wildlife: Flowers provide nectar and pollen for bees and other insects. Berries feed birds, often later in winter, while the dense evergreen branches provide shelter and nesting cover.

• Yellow leaves with green veins often indicate iron deficiency caused by alkaline soil. Test the soil; avoid repeated feeding as a substitute for correcting unsuitable conditions.
• Holly leaf miners leave pale blotches or winding marks within leaves. Damage is usually cosmetic; remove badly affected fallen leaves and avoid unnecessary insecticide use.
• Scale insects can cause sticky honeydew, sooty mould and weak growth. Check stems and leaf undersides, and treat confirmed infestations with a labelled horticultural oil at the appropriate stage.
• Root rot and dieback can develop in saturated soil. Improve drainage and keep mulch off the trunk; replace severely affected trees rather than replanting in the same wet conditions.

Toxic to people, cats, dogs and horses if eaten. Berries and leaves contain irritating compounds; berries are the most likely part to be swallowed. Ingestion usually causes gastrointestinal upset, including vomiting or diarrhoea in people, cats and dogs, and potentially colic in horses. Large amounts can cause more serious illness; contact a poison service or veterinarian after ingestion.

• English holly (Ilex aquifolium)

  Usually has glossier, darker leaves with more strongly rippled margins. American holly leaves are generally flatter and duller, although leaf shape varies on both species.

• Chinese holly (Ilex cornuta)

  Typically has glossy, roughly rectangular leaves with a few strong, horn-like spines. American holly usually has oval leaves with more numerous spines along the margins.

• Foster holly (Ilex × attenuata 'Fosteri')

  Usually has smaller, narrower leaves with fewer marginal spines and a more slender crown. It is a hybrid involving American holly and dahoon holly.

Ilex is the classical Latin name for holm oak, whose leaves resemble holly foliage, and opaca means dull or opaque, referring to the relatively matt leaves.

Propagation. Take semi-ripe cuttings in late summer, using rooting hormone and a humid, sheltered propagation setup; rooting can be slow. Seed requires lengthy warm and cold periods and may take two or more years to germinate. Use cuttings from a known plant to preserve its sex and characteristics.

Accepted botanical name

Ilex opaca

In the US and Canada

Native in the lower 48 states.

Native range

Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana and Maryland.

Measured

Soil pH 4.5 to 7. Average height 530 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.