Q: Why are my 'Crimson Pygmy' leaves turning green?
A: This is almost always due to insufficient sunlight. For the richest, deepest crimson-purple color, the shrub needs full sun (at least 6 hours of direct sun daily) . In partial shade, the foliage will fade to a greenish-red or bronze-green .

Q: How big does it get and how fast does it grow?
A: It is a moderate grower, typically reaching 2-3 feet in height and 3-4 feet in width at maturity . Its compact, dense form is naturally tidy and requires little to no pruning to maintain its shape .

Q: Is this plant invasive?
A: Yes, Japanese barberry (Berberis thunbergii), including this cultivar, is considered invasive in many parts of the United States and Canada . It spreads by seed (birds eat and disperse the berries) and by creeping roots . It can form dense thickets that displace native plants and alter soil chemistry. Check local regulations before planting. Consider native alternatives where invasiveness is a concern.

Q: How should I prune it?
A: Pruning is generally not required for health or shape. If you need to control size or rejuvenate an older plant, prune in late winter or early spring before new growth emerges . You can also trim it lightly after flowering. Always wear thick gloves and long sleeves, as the thorns are very sharp .

Q: Are the berries poisonous?
A: The berries are not considered highly toxic, but they contain berberine and can cause mild stomach upset if ingested in large quantities, especially in children . The RHS notes the fruit is ornamental and should not be eaten . It's best to plant with caution where small children are present. The main landscape concern is the plant's invasive potential, not its toxicity.