When we used to live in zone 6, for round, bush-like hollies we grew China Girls & one China Boy. They were suggested by a friend in the horticultural biz. You need the boy for pollination if you want berries. He's not as attractive as the girls & won't bear the berries, so place him in a less prominent spot. Hollies like water, extra iron & pruning, so keep that in mind. However, they look great through the winter, especially at Christmas time.
