This genus includes some 350 species and is best known for its spiny, evergreen forms with red berries. There are also deciduous selections. All are popular landscape plants whose berries often persist well into winter, and are especially striking against the snow.
Only the female plants produce berries. Give the females a prominent spot and tuck the male plant (which is necessary for pollination) in a less obvious one. A male plant can be up to 40′ from the female without reducing fruit set.
The so-called Blue Hollies (Ilex x meserveae) are hybrids between the English Holly, I. aquifolium, and a more cold-tolerant species from northern Japan (I. rugosa). They offer the glossy, spiny leaves of English Holly on plants that are hardier.
Grow Blue Hollies in full sun or light shade in average, well-drained soil. In cold-winter climates, plant in a spot protected from north winds. Prune in late winter or after bloom, but be aware that pruning reduces fruit production.
Winterberry Hollies (Ilex verticillata) are deciduous plants. Leaves are mid-green and quite unlike the prickly, shiny leaves of evergreen Hollies. In the fall, the leaves turn yellow, then drop to reveal dense clusters of bright red, berry-like fruits on the female plants.
Winterberry Holly grows in full sun, partial shade, and even quite dense shade (at some cost to flower and berry production). In the wild, it is found in wet soil, but it also grows well in average soil and tolerates a fair measure of drought once established. It does insist on acid soil. Prune in late winter or after bloom, but be aware that pruning reduces fruit production. Not a good choice in the desert Southwest.