Choosing Male & Female Holly
To get berries, buy at least one female holly for fruit and one compatible male to pollinate it — or choose a self-fertile variety like Burford or Nellie R. Stevens. The male and female must be compatible species and bloom at the same time.
Because holly is dioecious, buying for berries means buying with pollination in mind. The female plant produces the fruit; a male nearby supplies the pollen. One male can pollinate several females within about fifty feet, so you do not need a male for every female — but you do need at least one, and it must be a compatible species that blooms at the same time.
The clearest examples are the matched pairs: 'Blue Prince' pollinates 'Blue Princess'; 'Jim Dandy' pollinates early winterberries like 'Berry Poppins', while 'Southern Gentleman' pollinates late ones like 'Winter Red'. If you have room for only one plant and still want berries, buy a self-fertile holly — Burford and Dwarf Burford Chinese holly, or the hybrid Nellie R. Stevens — which fruits without a separate male.