Our Knockout Roses Are Out Of Control. Large At The Base Almost Like Regular Old Rose Bushes.

Question

How far can I cut them back without damaging or killing the whole bush?

Answer 1

This will be in Spring, and you can cut the plant back by about 1/3. Whether this be across the top, or just removing 1/3 of the plant's branches. Here is an article for more information:

https://www.gardeningknowhow.com/ornamental/flowers/knockout-roses/prune-knockout-roses.htm