Evergreens such as holly, with its bright green leaves and sparkling red berries, add excitement to an otherwise dull winter landscape. University of Illinois Extension horticulture educator Jennifer Fishburn provides insights on growing the winter favorite.
“Holly is the common name for the genus Ilex which has more than 800 species, including both evergreen and deciduous leaved species. Holly plants are a great addition to the landscape, but careful consideration must be given to the planting location. The ultimate size and shape of a mature plant is an important consideration, as the plants need ample space to grow,” Fishburn says.
Evergreen hollies can be planted in full sun or partial shade protected from winter sun and wind. They prefer a moist, organic, well-drained soil with an acidic pH. To keep hollies happy through Illinois winters, Fishburn advises gardeners to select cultivars which are hardy to your zone and to ensure plants receive ample moisture during dry periods.
Several holly species will provide colorful fruit for three to six months of the year. Fruit persistence depends on the bird and squirrel population in an area. Plants with yellow berries are often ignored by birds or are eaten after red fruits are gone.
Holly plants are dioecious, meaning both male and female plants are needed to ensure fruit production. Only the female produces fruit. It is important to have male and female plants that are closely related and flower at the same time.
“How do you know the sex of a plant? Male and female flowers have different parts. For some of us, this may be a little difficult to see, so we must rely upon retailers to correctly mark the plants,” Fishburn says. “Most cultivars have sex-appropriate names such as ‘China Boy.’”
Mature plants can be kept at a manageable size and shape by pruning them in late fall or early winter. Prune hollies after they have been established for several years, as new plants resent pruning. An added bonus of pruning is to collect the branches and use them as holiday decorations. Holly branches covered with berries look great in an outdoor container or on a fireplace mantel.
One of the better-suited hollies for Illinois landscape conditions is common winterberry, Ilex verticillata. Winterberry is a deciduous holly hardy to zone 3, with good pest and disease resistance. The rounded leaves will remain on the plant into late fall. Red berries begin their display in September and can last for several months. Cultivars vary in height from 5 to 10 feet. This species is a good selection for shrub borders or screening. Female plant selections with red fruit include ‘Red Sprite’, and Winter Red®. ‘Red Sprite’ is a shorter cultivar growing 3 to 5 feet tall. Winter Red® can get 8 to 9 feet tall and wide. A good male pollinator is ‘Jim Dandy,’ a dwarf, slow grower.
“If space permits, perk up your winter landscape with one of these great holly selections,” Fishburn says.