Winterberry holly (Ilex verticillata), like all hollies, is dioecious, meaning male and female flowers are borne on separate plants. You must plant one of each for the female to set fruit. Choose a male plant that blooms at the same time as the female.

Females to plant with I. v. ‘Jim Dandy’, an early-blooming male:
‘Afterglow’, for large orange-red berries in profusion
‘Aurantiaca’, for distinctive  orange-yellow fruit
‘Cacapon’, a heavy fruiter with scarlet berries
‘Nana’ (‘Red Sprite’), a dwarf form with masses of red fruit
‘Stoplight’, for glossy foliage and deep red fruit

Females to plant with I. v. ‘Southern Gentleman’, a late-blooming male:
‘Winter Gold’, for apricot orange fruit
‘Winter Red’, for profuse and persistent red fruit

Read more about winterberry holly