William Penn Barberry
Berberis gladwynensis 'William Penn'
Essentials
At a Glance
Plant Type
Shrub
Height
48 inches
Width
60 inches
Light
Full Sun, Partial Sun
Zones
6, 7, 8, 9
Water
Low to moderate
Humidity
Adaptable
Lifespan
20-30 years
Native To
Garden origin
Toxicity
Mildly toxic if ingested; spines are a skin irritant.
The Story
Plant Bio
Berberis x gladwynensis is a hybrid evergreen barberry, a cross between B. gagnepainii and B. verruculosa. It is known for its dense, arching habit and spiny stems. 'William Penn' is a popular cultivar valued for its glossy, dark green leaves that take on attractive bronze to reddish-purple tones in fall and winter. It forms a dense, mounding barrier hedge.
Bloom Period:
Uses & Benefits:
Marketplace
Where to Buy
Shipping costs Year-round shipping Free shipping
Planting
How to Grow
- Choose a location in full sun or part shade with good drainage.
- Dig a hole that is twice the width of the root ball.
- Set the plant in the hole, making sure the top of the root ball is level with the soil.
- Backfill with soil, firming it around the base of the plant.
- Water thoroughly after planting to eliminate air pockets.
- Mulch to conserve moisture, but keep it away from the stems.
Pro Tip
Wear thick, puncture-proof gloves when pruning or handling this shrub; the spines are sharp and can be painful.
Keep It Thriving
Care Guide
Do
- Plant in well-drained soil.
- Provide full sun for the best foliage color and density.
- Prune after flowering to maintain size and shape.
- Use as a barrier plant where you want to deter foot traffic.
Don't
- Don't plant in poorly drained or waterlogged soils.
- Avoid planting near walkways or play areas due to the sharp thorns.
- Don't prune late in the season, which can stimulate vulnerable new growth.
- Check for local restrictions, as some barberry species are invasive.
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fertilize | ||||||||||||
| Plant | ||||||||||||
| Prune |
Watch Out For
Pests & Diseases
Common Pests
Common Diseases
In the Garden
Landscape Uses & Companions
Landscape Uses
Companion Plants
Multiply
Propagation Methods
Good to Know
Common Questions
William Penn Barberry questions
What zones can William Penn Barberry grow in?
William Penn Barberry is hardy in USDA Zones 6–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Is William Penn Barberry deer resistant?
Yes — William Penn Barberry is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.
When does William Penn Barberry bloom?
William Penn Barberry typically blooms in mid-spring through late spring. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.
Does William Penn Barberry need full sun?
William Penn Barberry does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.
Is William Penn Barberry drought tolerant?
Yes — once established (usually after the first full season), William Penn Barberry handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.
More Berberis to compare
Keep exploring
Explore the genus
Collections featuring this plant
Hardy in your zone?
Grow William Penn Barberry with confidence
See it in a design of your actual yard, get zone-matched care reminders, and track it season by season in your garden journal.
