Winterberry holly leaves are dark green and elliptical, about two to three inches long. Greenish-white flowers appear on female plants in spring, which, if properly pollinated by a male plant, produce a dense crop of bright red berries in the fall. A slow-growing shrub with a rounded upright growth habit, winterberry typically grows 3 to 15 feet tall and readily suckers and spreads to form large thickets. It is generally planted in late summer to early fall, though spring planting is usually successful, as well. Winterberry holly is often associated with the Christmas holiday season and their berry-laden stems are used to add color to evergreen arrangements. Winterberry holly is toxic to people, dogs, cats, and horses. In nature, winterberry holly shrubs grow naturally in wetland areas, which makes them ideal for routinely moist or poorly drained areas of a home landscape where little else will grow. However, they’ll also grow in a variety of conditions, if they receive enough moisture. Winterberry is generally pest- and disease-resistant but can be susceptible to leaf spots and powdery mildew, which are rarely serious. Winterberry holly is a dioecious plant, which means that plants are gender specific, either male or female. Because only fertilized female plants will produce a wonderful display of berries, at least one male winterberry plant must be planted within 40 to 50 feet of a female for cross-pollination to occur. Generally, a single male shrub can pollinate six to ten female shrubs. When purchasing a winterberry holly, it is key that the male plant blooms at the same time as the female. Most quality garden centers include the gender on the plant tag so that you purchase the right pairs of plants.
Light
Winterberry holly will do well planted in a location with full sun to partial shade. To ensure ample flowering and fruiting, plant the shrub where it receives at least six to eight hours of sunlight per day.
Soil
This plant adapts to both light and heavy soils but performs best in acidic loam with a good level of organic material. It does poorly in neutral to alkaline soil, which can cause fatal chlorosis (yellowing of the leaves). Feeding it with a fertilizer designed for acid-loving plants can help modify soil pH levels if a soil test reveals soil that is neutral or too alkaline.
Water
Winterberry prefers fairly wet conditions. Do not plant it in dry soil or a dry climate unless you are willing to water frequently. This plant will require at least one inch of water per week, either through rainfall or irrigation.
Temperature and Humidity
Winterberry has a good tolerance for all temperature and humidity conditions across its hardiness range, though it does not do well in conditions of prolonged dryness.
Fertilizer
Winterberry holly usually doesn’t require feeding unless growth is very slow. Where needed, 1/2 cup of balanced 10-10-10 fertilizer applied each spring usually is sufficient. Feeding with a fertilizer designed for acid-loving plants can help modify soil pH levels if a soil test reveals soil that is neutral or too alkaline.
Types of Winterberry Holly
Planting one of the many good cultivars of winterberry holly might be better than planting the native species because the growth characteristics of the cultivars are often preferable. Buying from a reputable local nursery can also ensure that you purchase the right male plant, necessary for pollination and production of berries.
‘Oosterwijk’: This female Dutch cultivar is noted for branches that work well in floral displays, This variety grows four to six feet in height. It is pollinated by the male shrub ‘Southern Gentleman’. ‘Winter Red’: This female multi-stemmed shrub produces its red berries in abundance, Mature plants grow eight to nine feet in height. It is pollinated by the male shrubs ‘Apollo’ or ‘Southern Gentleman’. ‘Cacapon’: This female variety has attractive, dark, glossy green leaves and compact branching. Mature plants are 6 to 8 feet in height, with an appealing rounded growth habit. It is pollinated by the male shrubs ‘Apollo’, ‘Jim Dandy’ or ‘Southern Gentleman’. ‘Red Sprite’: This female great low mounded shrub grows to a moderate 3 to 5 feet in height, its branches remain dense right down to ground level, so it works well as a low hedge plant or in mass plantings. It is pollinated by the male shrub ‘Jim Dandy’. ‘Winter Gold’: As the name implies, this female cultivar sports yellow berries that turn lighter as they age. Mature shrubs will reach 5 to 8 feet in height. It is pollinated by the male shrub ‘Southern Gentleman’. ‘Aurantiaca’: This female shrub with bright pinkish-orange fruit grows six to eight feet in height. It is pollinated by the male shrub ‘Jim Dandy’. ‘Berry Poppins’: This dwarf female variety grows to just 3 to 4 feet in height. It is pollinated by the male shrub ‘Mr. Poppins’.
Pruning
Because the flowers (and resulting berries) appear on new growth, winterberry holly should be pruned to shape in early spring, just before new growth appears. Pruning is recommended because these shrubs not only grow tall, they also sucker profusely if not controlled. Remove up to (but no more than) 1/3 of the branches each year. Target the oldest branches, and prune them down to ground level.
Propagating Winterberry Holly
Although it’s tempting to try planting seeds produced by the plentiful berries, winterberry is more effectively propagated by cutting and rooting stem cuttings, which will grow much faster than seeds. Propagating winterberry holly is best done in late spring through mid-summer. Here’s how:
How to Get Winterberry Holly to Bloom and Produce Berries
Winterberry holly is primarily planted for its abundant and colorful berries, so it makes sense that you’d want to ensure the best show possible. A few factors directly impact how vigorously your winterberry holly will bloom, the first being the presence of compatible male and female varieties. Both genders will produce small green-white flowers in late spring which will eventually turn to berries on female plants if properly pollinated. To identify the female from the male shrubs, look at the center of their flowers: female plants will have a small green nub in the center while male plants will have pollen-bearing anthers. Regardless of gender, winterberry holly shrubs require pruning at the proper time of year in order to ensure a crop of berries. The plant blooms on old wood, which means the only time you should prune it is sporadically in the winter while the berries are still on the bush. But the best option is to plant the shrub somewhere where it can grow freely—that way, you don’t risk pruning off future blooms and berries. If your winterberry does not produce flowers or berries, it could be a gender issue: the right female and male pairs are not located close enough to each other. If you’re still not seeing berries or flowers on your shrubs—assuming all other care requirements are met (including the proper amount of sunlight and water)—the problem could lie in the age of the shrub. Winterberry hollies only fruit when they’re well established, which can mean as many as two to three years in the ground before you’re granted a showy display.
The berry-laden branches of Ilex verticillata are prized by arts and crafts enthusiasts for use in such items as floral arrangements, winter window boxes, wreaths, and kissing balls.
