Answer: Here's a good example of a pet peeve of mine: Companies that sell plants that don't have trained staff on hand to answer questions. There are literally dozens of different species of holly, and hundreds of cultivars. I couldn't find 'Blue Moon' on any of the several databases I consulted. So I can't tell you anything in particular about this plant.
By far, most hollies require a compatible male plant nearby to supply pollen if the female plant is going to produce berries. (A few types can produce berries without pollen, but they put on a better show if a male is nearby.) Since it is often impossible to tell a male from a female in young nursery plants, reputable nurseries will have specimens carefully labeled. Often the cultivar name gives you a hint--for example, 'Blue Prince' or ' 'Blue Boy' to indicate a male.
I suggest you ask to talk to the owner/manager of the nursery to get more info. They should be able to pursue it for you. Or, the name of the grower should be on the plant tag. They should also know. If you want berries, it would be a shame to have 6 female plants needing a pollinating male, with none nearby.
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