Winterberry holly Ilex verticillata
Winterberry holly (Ilex verticillata) is a deciduous perennial shrub in the Aquifoliaceae family, native to Eastern North America (swamps and wet woods). It grows 1.5–3 m (4.9–10 ft) tall and 1.5–3 m (4.9–10 ft) wide, wants full sun and high water, and is hardy to about -34 °C (-29 °F). Space plants about 1.8 m (5.9 ft) apart.
Plan Winterberry holly in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Winterberry holly at a glance
| Type | Perennial shrub, deciduous |
|---|---|
| Family | Aquifoliaceae |
| Mature height | 1.5–3 m (4.9–10 ft) |
| Mature spread | 1.5–3 m (4.9–10 ft) |
| Spacing | 1.8 m (5.9 ft) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | High; drought tolerance low, waterlogging tolerance high |
| Soil pH | 4.5–6.5 |
| Cold hardiness | About -34 °C (-29 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 33 °C (91 °F) |
| Flowering | from about June for 2–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Moderate |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Eastern North America (swamps and wet woods) |
| Common in gardens of | 🇺🇸 United States |
Is Winterberry holly toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: berries
Berries contain saponins and can cause vomiting, diarrhoea and drowsiness if eaten in quantity.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Winterberry holly
No well-documented helpful pairing. Group it with plants that like full sun and high water.
Questions about Winterberry holly
- How far apart should I plant Winterberry holly?
- About 1.8 m (5.9 ft) apart, centre to centre. A mature plant spreads 1.5–3 m (4.9–10 ft).
- Does Winterberry holly need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Winterberry holly need?
- High water. Drought tolerance is low and waterlogging tolerance high.
- How cold-hardy is Winterberry holly?
- It tolerates about -34 °C (-29 °F) once established, roughly USDA zone 4.
- When does Winterberry holly flower?
- From about June for 2–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Winterberry holly poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Berries contain saponins and can cause vomiting, diarrhoea and drowsiness if eaten in quantity.
- What grows well with Winterberry holly?
- There is no well-documented companion pairing for Winterberry holly. Group it with plants that like the same sun (full sun) and water (high).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- USDA PLANTS Database, USDA NRCS
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- Extension Gardener Plant Toolbox, NC State Extension
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
Notes and assumptions
- Dioecious: berries only form on female plants with a male pollinizer within about 15 m; the plant is not grown for a harvest.
- Typical garden-form values; cultivars and local conditions differ.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- English holly Ilex aquifolium
- Yerba mate Ilex paraguariensis
- Japanese holly (inutsuge) Ilex crenata
- Bigleaf hydrangea Hydrangea macrophylla
- Rhododendron Rhododendron
- Boxwood Buxus sempervirens
- Oleander Nerium oleander
- Common ninebark Physocarpus opulifolius