Maureen:

You can prune in the winter, or prune in the summer, or you can prune anytime. Summer pruning retards vigorous growth, while dormant pruning promotes it. So do you want more growth, or do you want to slow it down?

Aside from this general rule, you should prune trees if they need it, not neccessarily on any particular schedule. Trees that were planted last fall may not need much pruning, except to establish a good, well-spaced branch structure. Space out the branches that are to be your main scaffolds so that they do not shade or interfere with each other.

If your trees try to set a few plums this spring, watch out for the plum curculio.

Don Yellman, Great Falls, VA