Shira plum tree needs pruning
We moved into a house with a mature plum tree that is in sore need of pruning. It is December now so likely too late to prune, right? When is our next opportunity and how should we do it?
Multnomah County Oregon
Winter is not the only time to prune fruit trees, but it is an excellent time. And winter, for purposes of pruning, means "after the leaves have fallen off".
Right now there are still leaves on many fruit trees--they are not completely dormant, though they are certainly slowing waaaaay down. The concern about pruning just before the first frosty weather is that fruit trees, like most plants, respond to any amount of pruning by pushing out new growth--and new growth this time of year will probably be damaged by the arrival of freezing weather. So hold off for a few weeks; then you can prune any time in winter.
Or as wise pruners say, "Any time that your tools are sharp". Traditionally, the real reason that old-time farmers did so much pruning through the winter months was that it was a comparatively slow time in the farming business--not so many competing demands on the farmers' time.
Beyond this, pruning is one of those things, like cooking, that entails a great number of skills and tricks. And like cooking, it really can't be fully explained in a short article like this. Let me recommend an excellent resource for much more information: The American Horticultural Society Pruning & Training, by Christopher Brickell & David Joyce. It is easily available through your library (and that title is not a typo, the implied "book of" is actually not there). This excellent book describes plant growth, tools, best practices, and lots of color plant diagrams with little red marks that say "cut here".