The Holly (Ilex) genus is very popular among landscape architects, nurserymen and home gardeners. Horticulturalists recognize approximately 20 American Holly species, 120 Oriental species, and nearly 200 varieties of the English Holly.
Hollies offer quite a diverse range of plant characteristics. They can be deciduous or evergreen, small (18 inches) or large (over 50 feet), and may be rounded, globose, pyramidal or columnar in form. Landscape uses are just as varied; hollies can be used as foundation plantings, screening, hedges, accent plants, mass plantings or specimen trees.
Hollies are easily recognized by their alternate leaves. The flowers are generally inconspicuous with sexes on separate plants. It is essential to have both staminate and pistillate plants in the same general vicinity to insure proper pollination. Poor fruiting on hollies is a problem many gardeners experience. This could be due to poor pollination, young immature plants, high nitrogen levels in the soil, or a late spring frost which injures flowers.
The general culture of hollies is quite simple. Most holly cultivars require well-drained soil and like full sun. Be sure to know the cold hardiness limits of the particular holly, as many are not hardy past zone 7 (upper Piedmont area).
Good drainage is required, especially on the Japanese (crenata) hollies. Chinese (cornuta) and dwarf yaupon (vomitora nana) seem to tolerate wet feet much better. Plenty of organic matter, especially in sandy soils, will also be helpful. Holly beds should be well-mulched and fertilized with a complete fertilizer to remain healthy. The soil pH should be between 5.0 and 6.0.
Maintenance requirements will include pruning of the vigorous growing cultivars, and controlling leaf miner, Japanese wax scale, and redmites. Root rot diseases are a problem with several Japanese cultivars.
The following is a partial list of Hollies which grow well and are versatile in North Carolina landscapes.
|Botanical Name||Common Name||Landscape Remarks|
|Ilex x altenuata 'Fosteri'||Fosteri Holly||Cross between 1. cassine x opaca. Favorite upright, 'Stokes' - not as hardy as production. Popular as foundation planting on corners of structures.|
|Ilex aquifolilum||English Holly||Lustrous, dark green, spiny leaf. Many cultivars available.|
|Ilex cassine||Dahoon Holly||Excellent tree form, hardy to zone 9, red berries. Good for eastern North Carolina landscapes.|
|Ilex cornuta||Chinese Holly||Hardy to zone 7. Typically reaches 9-12' in height, medium to coarse texture. Favorite cultivars include:|
|'Burfordii' - heavy fruit crop, can get very large.|
|'Dwarf Burfordii' - 5-6', does not fruit as heavily as 'Burfordii'.|
|'Carissa' - dense, dwarf, 3-4' high.|
|'Rotunda' - compact, dense, spiny leaves; to 5' if not maintained.|
|Ilex crenata||Japanese Holly||Hardy to zone 6, can reach 9-12' in height, medium to fine texture (smaller leaves than cornuta). Dense, multi stem evergreen shrub. Favorite cultivars include:|
|'Compacta' - globose form, requires little pruning, to 6'.|
|'Convexa' - very hardy, dense, can grow to 9'.|
|'Green Luster' - dark green, lustrous foliage.|
|'Helleri' - low spreading, 3' height x 5' width.|
|'Hetzi' - more compact than 'Convexa'.|
|'Kingsville Green Cushion' - very low-spreading form.|
|'Microphylla' - hardy to zone 5 very small leaves.|
|'Rependens' - small, narrow leaves; maintained at 3' easily.|
|'Rotundifolia' - rounded form, easily reaches 8-12'.|
|'Stokes' - not as hardy as 'Helleri' but remains compact.|
|Ilex decidua||Possomhaw Holly||Deciduous large shrub (30') with crenately-toothed leaves. Fruits bright red or orange and very showy in fall and winter.|
|Ilex glabra||Inkberry||Grows 6-8' tall, rounded form, hardy all across North Carolina. Slow growth rate, black berries produced, showy in fall.|
|Ilex x 'Nellie R. Stevens'||Upright, pyramidal, dense small tree form. Hybrid between 1. aquifolium x 1. cornuta. Hardy to zone 6.|
|Ilex opaca||American Holly||Grows 50-60' tall, medium to coarse texture. Females fruit heavily in fall, needs 1 male for every 2-3 females; pyramidal form. Many cultivars available.|
|Ilex 'pernyi'||Perny Holly||Pyramidal, upright habit. 9-12' tall, hardy to zone 6.|
|Ilex verticullata||Sparkleberry||Deciduous shrub; withstands wet conditions, active to swampy areas fruit very showy in fall and winter. Several cultivars available.|
|Ilex vomitoria||Yaupon||Hardy to zone 7. Native to coastal areas; tree form reaches 15-20'. Translucent berries, gray bark.|
|Ilex vomitoria 'Nana'||Dwarf Yaupon||Low growing shrub form; very dense, branching habit.|
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Publication date: Sept. 30, 1994