I got an American Hornbeam from a nursery and have been trying to find information on timing for hard pruning and re-potting, but I am finding conflicting information.
When is a good time to hard prune? One source says to prune back in the winter while the tree is dormant. Thoughts?

What is the intent?

If you chop Between now and budbreak, and do not do any rootwork you can expect explosive growth in spring. THis is normally coarse growth which has a lot of space between nodes which is not ideal

If you chop between now and budbreak, and do do rootwork, you will get slower regrowth. However, there is a risk of low number of buds pushing

If you do rootwork just before budbreak and trim in mid-summer, you would have newly established roots, yet slow regrowth with narrow internodes. Still a risk that the tree has trouble pushing buds.

I would probably not do rootwork. Prune in late spring (When growth slows down). Alow the tree to regrow for the rest of summer. Next spring, before budbreak, do rootwork.

Cool, thanks for the advice! I'll probably chop the tree late winter, just before spring to avoid frost and let it grow all year. Then see about doing root work next spring.