Illustration
American Holly
Ilex opaca
Also called american tree holly
American Holly blooms from May through May.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing American Holly
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–9. Expect it to reach about 35 ft tall and 20 ft wide at maturity, in roughly 40 years (checked).
Is American Holly toxic to dogs or cats?
- Listed as toxic to dogs and cats by NC State Extension and Pet Poison Helpline.
- Listed as poisonous to people by NC State Extension.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant American Holly
Plant American Holly in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 7, the middle of its hardy zones 5 to 9, spring means March to May and fall means September or October. Once settled, it blooms in May.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 7, the middle of this plant's hardy range, start with zone 7 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does American Holly get?
35 fttall5 ft 7 inan adult20 ftwideSee American Holly in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant American Holly
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Give American Holly about 20 ft of clear ground in every direction, measured from its center. It is one plant with room around it, not a row, and a raised bed is too small for it.
Add American Holly to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
American Holly's height, spread, hardiness zones, sun, water, bloom months and color, years to mature size and trait tags were checked against 8 published sources on October 21, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- edis.ifas.ufl.eduUniversity of Florida IFAS Extension, ENH463height, spread, hardiness zones, sun, water, bloom months and color and years to mature size
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- The Morton Arboretumheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- NC State ExtensionGardener Plant Toolboxheight, spread, hardiness zones, water, bloom months and color and trait tags
- kansasplantfarm.comKansas Plant Farm (Lawrence, Kansas)height, spread, hardiness zones, water and bloom months and color
- woodyplants.cals.cornell.eduCornell University Woody Plants Databaseheight, spread, hardiness zones, sun and water
- RHSRoyal Horticultural Societyheight, water and bloom months and color
- University of Illinois ExtensionKen Johnsonheight, hardiness zones and sun
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 27 states
United States: Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia, West Virginia and 15 more
Recorded growing wild in 757 counties.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
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