Many hundreds of species and hybrids exist. Smaller kinds are attractive as foundation plantings or low hedges; larger evergreen sorts make attractive and impenetrable tall hedges or screens. In size, they range from foot-high dwarfs to trees 40–50 ft. tall.
Nearly all holly plants are either male or female, and as a rule both sexes must be present in order for female plants to set fruit. Best bet is to plant a male of the same species as the fruiting females; if you use a different species, berries will form only if both plants flower at the same time.
Most hollies prefer rich, slightly acid garden soil with good water drainage. (A few exceptions are noted.) All appreciate a mulch to deter weeds and keep soil cool and moist. Though plants will grow in sun or part shade, choose a sunny spot for best berry production and most compact growth. Scale can cause problems in all holly-growing areas. Holly bud moth and leaf miner need attention on English holly in the Northwest; for control, employ only products currently registered for use against those pests. Diseases are rarely a problem for home gardeners.
Most hollies tend to be dense and symmetrical. Prune mainly to remove poorly placed, broken, or dead branches. Winter holiday season is a good time to prune, because clipped branches can be used for indoor decoration. You can restore a holly that has become too open or ragged by severely shortening its branches and allowing new growth to fill in. Small-leafed hollies can be sheared into formal hedges or topiary figures.
Evergreen shrub from Russia, Japan, and Korea. Looks more like boxwood (Buxus) than holly. Dense, erect, usually to 4–10 ft. tall and wide, sometimes much larger. Narrow, finely toothed, 1/2–1-in.-long leaves. Black berries. Extremely useful where winter cold limits the choice of polished evergreens for hedges and edgings. Varieties include the following.
‘Compacta’: Rounded shrub to 6 ft. tall and wide, with dense habit. Many different plants are sold under this name.
‘Convexa’: Compact, rounded shrub grows to 4–6 ft. tall and somewhat wider. Leaves are roundish, cupped downward at the edges. Use as a clipped or unclipped hedge. Many different plants are sold under this name.
‘Drops of Gold’: Grows to 3 ft. high and 6 ft. wide; yellow outer leaves and green inner leaves.
‘Helleri’: Remains very small (about 1 ft. high and 2 ft. wide) for many years. May reach twice that size in 30 years.
‘Sky Pencil’: Columnar plant to 6 ft. tall and only 10 in. wide.
Evergreen shrub from Russia, Japan, and Korea. Looks more like boxwood (Buxus) than holly. De...
Compact mound to 8–10 in. tall and 1 ft. wide. Reddish bronze, 1 1/2-in. leaves form a dark back...
Deciduous. This 40-ft.-tall, 20-ft.-wide hybrid of M. acuminata and M. x br...