Answer: There are certainly two ways to approach pruning hollies. First of all, keep in mind that the hollies will form berries based on where they have bloomed.
If you wish to have a sculpted look, you can trim the hollies by shearing or an overall trim. This may snip some of the individual leaves in half, which some people find unsightly. It is also more stressful to the plant over time and will result in an outer shell of foliage covering a bare internal structure of branches.
The other method is to reach into the shrub and trim out individual branches at their origin, aiming for an overall form with a slightly less rigid outline than would result from shearing. This is a matter of taste to some extent, as hollies will generally tolerate both types of treatment, but the second method is healthier for the plant.
You can prune holly most of the year (even in winter for decorations). Fall pruning should be avoided however so as to allow any new growth time to harden before winter weather sets in.
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