More than 150 species of holly can be found throughout North America, Europe and Asia. The two most popular species, American and English holly, have storied associations with midwinter festivals, including modern Christmas celebrations. While both of these species are known for being evergreen and for their bright red berries, other species lose their leaves in the winter and produce yellow or even black berries.
History and Meaning
Words for holly appear in ancient Germanic and Gaelic languages, and the modern word comes from Old High German and Old English. Holly played an important symbolic role in winter celebrations and continues to do so today. Because most hollies retain their verdant foliage and bright red berries throughout the bleak and barren winter season, to many people, the holly tree represents the continuation of life even through times of darkness.
In the United States, holly grows in the wild on the east coast, from northern Florida to New England and as far west as Texas, although it can be planted in all but the coldest parts of the country. In Europe, holly trees are most prevalent in the west, near the coast. As an evergreen that produces berries throughout the winter, holly serves as shelter and as a food source for wild birds. Holly flowers in late spring and, if cross-pollinated, will produce berries during the winter.
According to the Arbor Day Foundation, the American Holly tree serves as a versatile plant that can adjust to a range of conditions. Although it grows best with adequate rainfall, it is able to tolerate both droughts and flooded conditions. Likewise, holly trees can grow in full sun or thrive under the shady canopies of larger trees. If left to grow as a tree, the American holly will reach heights of 50 feet and develop a conical shape, but it can also be pruned and maintained as a hedge. If you want your holly to produce its distinctive red berries, you must plant multiple trees since holly trees develop as male and female plants, and both are required to produce berries. For example, the Arbor Day Foundation recommends planting at least four American Holly trees to guarantee berries.
Holly plants require very little care aside from pruning them to keep a particular shape, if desired. As trees age, they tend to lose their conical shape, so some homeowners may want to prune older trees. According to expert gardener Jeff Ball on the American Forests website, winter is the best time to prune holly because the plant is dormant. He also recommends mulching the holly tree with used coffee grounds and taking care not to overfertilize the tree.
The brilliant berries of the holly tree are iconic holiday decorations, but they are also toxic, so gardeners should take care with children and pets. According to Sara Williams, a horticulture specialist writing on the the University of Saskatchewan's website, as few as 20 berries may be lethal because they exert a depressive effect on the nervous system. Lower doses produce vomiting, diarrhea, drowsiness and coma.