The Growth Cycle of an American Holly

Two Plants

• Some holly species are self-fruitful, which means they do not require a male and female plant for cross-pollination to set fruit, or berries. American hollies are self-unfruitful; for a female plant to produce berries, a male plant is required for pollination. According to the Texas Parks and Wildlife website, male hollies outnumber females ten to one. Most nurseries label hollies as male or female, and some labels include the cultivar name. “Jersey Knight” is a good pollinator for American holly.

Propagation

• American hollies propagated from seeds exhibit a significant amount of variation, says Alex Niemiera of Virginia Cooperative Extension. Most horticulturists propagate American hollies by asexual propagation, such as stem cuttings, grafting or tissue-culture micropropagation. Although its growth cycle continues in the wild without asexual propagation, seed germination rates are quite low and second-generation plants may display different characteristics from their parent plants. “Old Heavy Berry” is offered in the nursery trade as a reliable, heavy-fruiting and vigorous female American holly cultivar, or cultivated variety.

Plant Growth

• Wild American holly seedlings form a deep taproot at a young age, which makes transplanting wild hollies difficult. Taproot formation helps establish young plants early in their growth cycle by facilitating their drought resistance. Although American hollies have heavier fruit production when grown in full sun, they can also grow in shade as understory plants. Fairly slow growing, they can reach heights of up to 50 feet and prefer acidic soil. According to The Smithsonian National Zoological Park website, American holly can live up to 100 years.

Flowers and Berries

• American hollies produce small white flowers in clusters in the leaf axils, where leaves join stems. Male plants must be close enough to female plants for wind or insects to transfer pollen from their flowers to flowers of female plants. Flowers are usually fragrant. Following successful pollination, bright-red berries form on female plants.