Question
I have 7 knockouts that are 3 years old. They are fantastic bloomers but are very tall and leggy (almost empty looking in the middle). I have had the occasional issue but have always kept under control with a spray and a 3 in 1 fertilizer 4 times a year.  My question is: It is July, can I trim it back without damaging it - and if so how much? FYI - I am in Atlanta Georgia.
Thanks!

Answer
Pruning is done basically in the spring because that is when the rose has the most energy and will overcome any pruning mistakes. It also increases the vigor of the rose. You can also prune hard in the summer but you will not get the same type of vigour as the spring. What will happen is that the rose will replace the canes slowly. Many gardeners do prune in summer to keep unruly or very vigorous roses under control such as climbers. To get your roses to bush out, you will have to prune back by a half. Then keep an eye out during the summer and if  they throw out a cane that is very tall, cut it back even with the rest of them. The reason your Knock Out roses are leggy is because if a rose puts out a tall cane, that cane becomes the dominant one and so draws up the bush instead of making it thicker. Water well after pruning.