What perennials to prune in the fall

Asked September 15, 2019, 1:11 PM EDT

We bought a house in Sisters two years ago and did major landscaping this spring. I planted vine clematis, hydrangea, brown (or black) eyed susan, mock orange, lilac, shasta daisy, yarrow, and various lupine. Which should be pruned, at what date, and how much of the plant should be pruned? Should I do anything to protect them from our harsh winter? Follow up question: last year we planted ten arbor vitae, all about six feet high. They grew almost none the first summer, but this summer they all sent up thin branches 10 to 14 inches. No measurable growth on the sides of the trees. What should I do to protect them from the winter? Last February we had heavy, deep snow and I was constantly knocking the snow off those trees so the branches didn't break. Any advice?

Deschutes County Oregon pruning horticulture perennials

2 Responses

Wow, this is a question for a pruning class. To best answer your pruning questions I am attaching two links, one for perennials and one for shrubs. If you go to page nine in the shrub attachment you will get to the nitty-gritty of pruning each type of shrub you list. There is a ton of important information in pages 1-8 that I advise you read if pruning is new to you.
https://extension.oregonstate.edu/gardening/flowers-shrubs-trees/winter-care-perennials
https://extension.oregonstate.edu/sites/default/files/documents/8226/pruning-packet.pdf

After studying these publications you just have to go out there and try your hand at pruning. Have fun!




Sorry, I forgot to address the Arbor Vitae question. In heavy snow it is suggested to tie a sturdy cord or rope around the outside of the plants to keep them from falling away from the centerline. Generally, you would start at the bottom of the plant, circling the plant a couple of times toward the top and then work your way back down and tie off the cord. Do not tie it super tight around the base and be sure to unwrap it once danger of snow ceases.