my blue princess and another christmas holly plant produce berries but have not grown taller over the years?

Question

They are close to ten years old, in partial shade. What to do to get them to grow tall?

Answer 1

These are notoriously slow growing. If it is producing plenty of berries, then it is signalling that it is healthy.

Unfortunately, these are doing exactly as they should be, so in order to get a taller shrub, you will have to get a variety that grows taller, faster.

This article will give you more information on the different Holly types: https://www.gardeningknowhow.com/ornamental/shrubs/holly/common-types-of-holly.htm