The American Holly Tree - Range, Growing Requirements, and Ecology

The American Holly is an adaptable plant.  It grows naturally as an understory plant, and tolerate quite a lot of shade.  It can even grow under a closed forest canopy.

This species is not picky about soil.  It grows well in both wet and dry soils, and can tolerate quite nutrient-poor soils.  It is somewhat tolerant of salt spray: much more so than most other forest trees.

It tolerates pruning well, and can even be grown as a hedge.

In areas where deer or other grazing animals damage gardens, this is a good tree to plant: its tough, thorny leaves are usually ignored by deer unless no other food is available.

In most of its native range, this tree thrives with little care.  Towards the north end of its range, and especially when planted farther north than it naturally occurs, protection from cold is a major issue.  The most damaging conditions for this plant are cold, windy days when the soil is frozen.  When growing this plant in the colder parts of its range, plant it in as sheltered a location as possible.  This tree is the most cold-hardy of the large broadleaf evergreen trees.  It can be grown significantly farther north than the Southern Magnolia.

In the past, it was common for gardeners and landscapers in the U.S. to plant a variety of non-native hollies, including the English Holly, and various Asian species of holly.

Even when they grow well, these plants are a poor ecological choice, because they do not support as many native insects and spiders, and thus, do not support as many native birds.  In some parts of the U.S., some holly species can become invasive.  In other parts, they don't grow as well.

Advantages of planting Native Hollies:

The American Holly is the most cold-hardy of all the large hollies.  It can be grown farther north and in colder regions than any other large holly.  I have even seen these trees growing in Cleveland, Ohio.

But the biggest advantage of using native plants are the benefits to the local ecosystems.

The berries of the American Holly are highly valued by native birds, such as the American Robin and Northern Mockingbird, as they are on the tree in winter when fewer food sources are available.  Small mammals also sometimes eat the seeds.

Planting an American Holly is one of the most reliable ways to attract fruit-loving birds to your yard in winter.  The dense evergreen foliage also provides shelter for animals during winter months.

The flowers, which are inconspicuous but sweet smelling, attract native pollinators including bees during the day and moths at night.

The tree also provides numerous other benefits to wildlife.  In the southeast, the endangered Red Cockaded woodpecker will nest in this tree.

The American holly is a large tree, not suitable for every site.  In warm climates, it requires either a lot of space or active pruning.  If you want a smaller tree, I recommend checking out some of the other species:

• Inkberry (Ilex glabra) - A small, compact evergreen bush.  Makes an outstanding landscape plant where space is an issue, such as in small areas around buildings.
• American Winterberry (Ilex verticillata) - A deciducous holly (losing its leaves), very cold hardy, and able to be grown at high elevations and farther north than any evergreen species can survive.  Naturally occurs into Canada, Wisconsin and Minnesota, and Maine.
• Yaupon (Ilex vomitoria) - A small evergreen holly native to the southeastern U.S., Yaupon is the only plant native to North America that is used to produce a caffeinated drink.

In very cold climates (Minnesota, Canada, etc.) it may not be possible to grow the evergreen species, but Winterberry is a better option.