Is it deer resistant?

Yes

Korean Barberry is deer resistant.

Berberis koreana

Deer: Rarely
Height: 6 ft (1.8 m)
Spread: 6 ft (1.8 m)
Zones: 3–8
Light: Full sun

Perennial
Shrub

Korean Barberry (Berberis koreana)

Photo: Krzysztof Ziarnek, Kenraiz · CC BY-SA 4.0

More details

Light: Full sun, Partial shade
Water: Low, Medium
Type: Perennial, Shrub
Maintenance: Low
Growth: Medium
Bloom: Spring
Foliage: Evergreen
Features: Drought tolerant, Flowering
Best uses: Barrier, Border, Hedge, Mass planting

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