It is about time that someone reintroduced this technique! Blue Princess holly is now available together in the same pot as its male pollinator, Blue Prince holly (Ilex x meserveae ‘Blue Princess’ and ‘Blue Prince’). With careful pruning to prevent one from crowding out the other, both can coexist and provide profuse, bright red berries every winter, indefinitely. As the plants grow, their main trunks will eventually graft together.
Blue Princess holly is purported to be the shrubbier of the two. Blue Prince might be a bit more compact, and might grow a bit slower. Both eventually get about seven feet tall and nearly as broad, with remarkably glossy evergreen foliage. Their rather wavy leaves have sharply pointed teeth. Fortunately, their teeth are not quite as sharp as those of traditional English holly, which happens to be one of their mutual parents.
If possible, it might be helpful to identify the two cultivars of holly in a mixed planting, and label them so that neither one nor the other gets pruned out. Blue Prince will be the plant that produces no berries. Of course, with selective pruning ‘Blue Prince’ can be confined and subordinated to the showier ‘Blue Princess’. Individual ‘Blue Princess’ holly plants are better for hedges, with separate ‘Blue Prince’ plants nearby.