Answer: It is true, there are separate male and female hollies; only the females produce berries. Males flower, but the flowers are inconspicuous so you really have to look hard. I cannot find any reference on the Monrovia website to indicate Ilex x meserveae 'Blue Boy' produces berries. In fact, the plant description reads as follows: Handsome hedge, background plant or specimen desired for its rich deeply colored foliage and stems. Excellent pollenizer for nearby female Hollies. Evergreen. Full to partial sun. Moderate grower to 6 to 8 feet high, 3 to 6 feet wide. If you look at the photo, the unopened flower buds at the tips of the stems might appear to be tiny berries, but they are actually unopened flower buds. This plant will never produce berries. But if it is planted near a female blue holly, such as Blue Girl, the Blue Girl will produce berries.
If both shrubs had berries when you purchased them, the one labeled Blue Boy was obviously a female. So you probably do have two females; in order for them to produce berries, you'll need a male plant.
Transplanting or environmental stress can keep plants from growing and producing flowers. I suspect that both will flower next year and, if you plant a male, both females will produce berries.
Best wishes with your hollies!
Q&A Library Searching Tips