Question
I recently purchased a house in Kansas City that has several large knockout rose bushes surrounding the property.  They are overgrown now can I trim them back and if so how much can I trim back.

Answer
When you prune a rose in the spring you do it to activate new growth as that is the time the rose grow the most. When you prune in the summer you do it to keep the rose down to the size you want. Pruning your roses now will keep them under control so go ahead and do it. If you want them to be around three feet then cut them back to about 18 inches, If you want them to be about 2 feet then cut them back to 12 inches. They will replace the growth in a couple of months. Knock Out roses will probably grow to about 4 1/2 feet in your area without any pruning.