Holly is a plant often associated with the Christmas season. Their glossy, green leaves and brightly-colored fruit are often used in wreaths, centerpieces, and other decorations. Unfortunately, most holly species are not reliably hardy in Iowa. However, winterberry, inkberry, and several Meserve hybrid hollies can be successfully grown in the state.
The flowers of all holly species are small and inconspicuous. Hollies are also dioecious. Dioecious plant species produce male and female flowers on separate plants. Only the female plants produce the attractive fruit. However, a male plant is required for pollination and fruit set.
Winterberry (Ilex verticillata) is native to much of the eastern United States, including areas in north central and northeast Iowa. While most hollies are evergreen, winterberry loses its leaves in the fall. It grows 6 to 10 feet tall. The fruit on female plants turn a bright red in fall and persist into winter.
Gardeners can choose from several female varieties noted for their excellent fruit display. 'Sparkleberry' is a large, upright shrub. It may become leggy with age as it may reach a height of 10 to 12 feet. 'Sparkleberry' produces brilliant red, 3/8 inch diameter fruit. Another excellent red- fruited variety is 'Winter Red.' 'Winter Red' is a rounded, 6- to 9-foot-tall shrub with dark green leaves and bright red, 3/8 inch diameter fruit. 'Afterglow' is a slow-growing, globe-shaped shrub with orange to orange-red fruit. Its mature height is approximately 6 to 8 feet. Where a small shrub is required, 'Red Sprite' is a good choice. 'Red Sprite' is a compact, globe-shaped shrub that grows about 3 feet tall. It produces red, 1/2 inch diameter fruit.
When planting hollies, a male variety must be planted for pollination and fruit set. One male plant is adequate for 6 to 8 female plants. 'Jim Dandy' is a suitable male variety for 'Afterglow' and 'Red Sprite.' 'Southern Gentlemen' is a male selection used to pollinate 'Winter Red' and 'Sparkleberry.'
Winterberry performs best in moist, acid soils in partial shade to full sun. Best fruiting occurs in those areas that receive at least 6 hours of sun. In alkaline soils, winterberry leaves may become chlorotic or turn a yellow-green. Chlorosis can be prevented by incorporating Canadian sphagnum peat moss into the soil of the planting area before planting.
Unlike many hollies, inkberry (Ilex glabra) is not grown for its fruit. Inkberry is an evergreen holly with dark green foliage and black, berry-like fruit. Plants grow 6 to 8 feet tall. While inkberry is evergreen, in Iowa it will oftentimes lose its leaves in winter during extreme cold. It is best used in protected areas as an accent or specimen plant in the home landscape. 'Compacta' is a dwarf female variety that grows 3 to 4 feet tall. 'Nordic' is a compact, rounded shrub with lustrous dark green foliage. It grows 3 to 4 feet tall. Inkberry requires a moist, acid soil in partial shade to full sun.
Several hybrid broadleaf evergreen hollies, collectively known as Meserve hybrid hollies, can also be grown in Iowa. 'Blue Prince,' 'Blue Princess,' Blue Maid , and Blue Stallion have dark, bluish green foliage and are often referred to as blue hollies. The female varieties have attractive red fruit. For gardeners with limited space, 'Berri-Magic Kids' contains a male ('Blue Boy') and a female ('Blue Girl') in one container. Other attractive Meserve hybrids include China Boy and China Girl .
Meserve hollies are variable in height. Most varieties grow 5 to 10 feet tall. They are hardy in USDA Hardiness Zone 5. However, they are susceptible to desiccation injury from bright sun and cold, dry winds in winter. Meserve hollies should be planted in protected sites, such as on the east sides of buildings.
This article originally appeared in the May 19, 2000 issue, pp. 58-59.