Q.Stemmed Holly Bush would like to know how to prune
How do I shape my holly trees ? into a round ball. Also the leaves on one of the trees has started to go yellow & drop off. I was wondering do I need to repot or feed the tree. I bought the pair of trees last year & have only watered them.

Certified GKH Gardening Expert
Round isn't usually the best shape for plants because the lower part doesn't get enough light. Plus, hollies aren't the shrub/tree of choice for topiary shapes. Those recommended are boxwood, yews, dwarf Alberta spruce, and arborvitae.
https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-yellow-leaves.htm
https://www.gardeningknowhow.com/ornamental/shrubs/holly/fertilizing-holly-bushes.htm
https://www.gardeningknowhow.com/garden-how-to/projects/how-to-make-your-own-topiary.htm
https://www.gardeningknowhow.com/ornamental/shrubs/holly/american-holly-trees.htm