You need to know how to prune knockout roses properly each spring, or late winter, so they will bloom profusely all season long.
Pruning knockout roses is best done while the knockout roses are still dormant, and not actively growing.
You should start with a sharp, clean pair of hand-held pruning shears that have curved bypass-type pruning blades .
Most pruning shears can cut stems up to half an inch in diameter.
For thicker canes, you'll need a pair of long-handled lopping shears .
I also find that having a fine-toothed pruning saw comes in very handy for removing old canes close to the base.
And most important, you need a pair of sturdy thorn-proof gloves. I prefer the gauntlet-style rose gloves, because they protect your forearms and wrists as well as your hands.
Knockout roses are shrub roses, which is a diverse group of roses with varying pruning needs.
After having pruned my knockout roses for many years now, I have found that they benefit from having one or two of their oldest, and less productive, canes removed each year.
Removing those old canes at the base, using a pruning saw, is the easiest way to do it.
This will encourrage new canes to grow, and newer fresh canes always produces the most blooms.
Overall, trim the knockout rose plant to create a pleasing natural shape and outline.
I garden in Los Angeles, California, and my knockout roses grow quite large here. Much taller than in cooler climates.
So therefore I cut them down to about half, each January, but you can also cut down about a third of last season's growth.
There are basically two types of pruning cuts to be made: Thinning Cuts and Heading Cuts.
A thinning cut removes a cane from where it emerges from the main cane, or from the base of the plant.
This type of cut is used to remove old, spindly, or twiggy growth. The main thing is to open up the center of the bush.
I always remove all smaller canes growing out from the 5-7 main canes that I decide to keep.
A heading cut is a cut made above a bud at a slight angle that slopes away from the bud.
When you prune to a bud that points away from the center of the plant it helps to encourage outward growth, which is desirable on most rose bushes.
I recommend sealing pruning cuts with either glue or clear nail polish on canes that are 1/8 in diameter.
This will prevent cane borers from entering the canes and cause diebacks.
Every pruning session should start with cutting out any dead, damages or diseased wood.
If two canes are rubbing against each other, remove one of them.
When you are finished pruning the dormant knockout roses, trim off any remaining foilage, and clean up the dropped trimmings.
Congratulations! You now know how to prune knockout roses.