Holly, with its distinctive pointed leaves and bright red berries, is a common sight at this time of year, at least on holiday cards and wrappings. Can you grow it in your garden?
“That depends on choosing the right kind of holly,” said Spencer Campbell, manager of the Plant Clinic at The Morton Arboretum in Lisle. Not all holly species are winter-hardy in Chicago, where nighttime temperatures can plunge down to the teens or below, as they did in early December.
The holly traditionally associated with Christmas — the plant that figures so prominently in Charles Dickens’ “A Christmas Carol” and in the old song “The Holly and the Ivy” — is English holly (Ilex aquifolium), native to England and other parts of Europe, North Africa and western Asia. Because it is adapted to climates with milder winters, the plant is not reliably hardy in the Chicago area, which is mostly in USDA winter hardiness Zone 5. In the Pacific Northwest, where winters are not as harsh as Chicago’s and most areas are in the warmer Zones 6, 7 and 8, English holly thrives so well that it has escaped from cultivation and become an invasive plant threatening native ecosystems.
Even without the English species, you can still have holly. “There are other plants in the genus Ilex with similar leaves and berries that will work much better here,” Campbell said.
To get berries on any holly shrub, you will need both male and female plants; the male plant provides pollen so the female plant can bear fruit. Hollies also prefer acidic soil, rather than the alkaline soil most common in the Chicago region, so check your soil pH before you start shopping. Here are some holly possibilities to consider. For more information on each of these plants, search on the Arboretum’s website at mortonarb.org.
Meserve holly (Ilex x meserveae): This is a group of shrubs, also called blue hollies, that are hybrids between English and Asian holly species. They look like traditional English hollies, with dark, shiny blue-green leaves, but are much more cold-hardy and are not known to be invasive. There are several cultivars, or cultivated varieties, with different sizes and habits. Blue Princess holly (Ilex x meserveae ‘Blue Princess‘) grows 8 to 10 feet tall, while Blue Girl holly (Ilex x meserveae ‘Blue Girl’) tops out at 6 to 8 feet. Each female cultivar has an appropriate male pollinator, such as Blue Prince holly (Ilex x meserveae ‘Blue Prince’) for Blue Princess holly. Sometimes, both male and female plants can be purchased in the same pot.
Common winterberry (Ilex verticillata): This Chicago-area native has spectacular red berries on bare black branches. “It’s a deciduous shrub that drops its leaves in winter,” Campbell said. Birds love the berries, so you may have to move quickly to capture some branches to tuck among other evergreens in your holiday decorating. The straight species of winterberry, which grows in moist, acid soil at the edge of bogs, is a large shrub, but cultivars, such as Winter Red, Berry Nice and Red Sprite, are widely available in a range of sizes. Male pollinators include Jim Dandy and Southern Gentleman.
American holly (Ilex opaca): This large shrub or tree has a holly’s classic pointy-edged evergreen leaves and red berries. Native to warmer southern regions of the United States, it is considered only marginally hardy in USDA Zone 5 and isn’t often available in the Chicago area, although it does grow at the Arboretum in the western suburbs. It’s a big plant. “In the South, it can grow 40 feet tall and wide, although it probably wouldn’t get that big around here,” Campbell said. “You would need a lot of space, especially since you need two plants to get fruit.”
Oregon grape-holly (Mahonia aquifolium). “This plant isn’t really a holly, but its leaves have that look,” he said — dark blue-green, glossy and pointy. It does not have red berries, but rather yellow spring flowers followed by dark blue fruit. A low-growing shrub native to the western United States, Oregon grape-holly is considered winter-hardy in USDA Zone 5, but not in colder zones. It does best in a protected site in part sun or shade. Unlike true hollies, it does not require a separate male pollinator plant to bear fruit.
For tree and plant advice, see the online resources of The Morton Arboretum at mortonarb.org/plant-care, or submit your questions online at mortonarb.org/plant-clinic or by email to plantclinic@mortonarb.org. Beth Botts is a staff writer at the Arboretum.