Can You Prune Knock Out Roses to the Ground?

When to Prune

• There are certain conditions when it’s acceptable to prune Knock Out roses, or any roses, for that matter, to the ground. When you find dead, diseased, damaged or weak canes (another word for a rose bush’s flexible branches), you can prune Knock Out roses back to the ground. Identifying a dead cane is fairly easy; it will be brown or gray in color and brittle rather than flexible. Diseased canes are generally discolored. Damaged canes may have been damaged either by weather, such as cold temperatures or high winds, or by pests, evident by deformed or discolored growth and deformed buds and/or leaves. Weak canes are those that are thinner than a pencil. Every few years, you should remove some of the oldest canes at the base as well. Prune only the canes that are problematic, and leave the healthy canes alone.

When Not to Prune

• If you’re simply looking to create or maintain a fuller shrub, then pruning Knock Out roses isn’t the best idea. Instead, you should prune the canes back to about 1 foot or so from the ground. This may seem a bit drastic, but the vigorous growth habit of a Knock Out rose bush will have it back to its original size in no time. You don’t need to deadhead Knock Out roses (meaning to remove the spent blossoms once they’ve finished flowering), but you can do it in order to neaten up the plant.

Proper Timing

• Like most roses, timing is important when pruning Knock Out roses. Dead, diseased and damaged wood, especially damage caused by pests, can be removed at any time. Deadheading can be done at any time during the growing season. When pruning Knock Out roses to create a fuller shape or when removing old or weak wood, the best time to prune Knock Out roses is in early spring, just as the buds are starting to swell but before the shrub has actually leafed out. Pruning Knock Out roses every year isn’t necessary; every three years or so should suffice.

Proper Technique

• Use a pair of clean, sharp bypass pruners to prune Knock Out roses. Clean your pruners after you’ve removed dead, diseased or damaged wood and before moving from one shrub to another to prevent the spread of disease. Dispose of rose cuttings in the garbage immediately; don’t leave them at the base of the plant or put them in the compost. Make cuts at a 45-degree angle just above a healthy bud that faces outward rather than inward.