Some gardeners say that the wildly popular Knock Out rose variety is over-planted.

If you look around town at what is blooming now, you might find a Knock Out rose on what seems like every corner (and maybe even in your own garden).

Love it or hate it, the Knock Out has changed the face of the landscape across much of the U.S. since its introduction in 2000. Despite being followed by a number of quality performers, it is and probably always will be the most widely sold rose in North America.

Gardeners and landscapers love Knock Out roses for their long bloom season and low maintenance requirements. They transplant easily, stand up well in heat and drought, and just keep blooming their hearts out through the summer. OK, maybe the blooms after the first flush are a little more sparse than described, plants get a little more black spot disease than hoped, and plants get a little bigger than expected. Overall the plant is still a winner.

On the other hand, gardeners and landscapers dislike Knock Out because there are even better options out there and they feel the rose is over-planted. Some of the newer introductions of shrub roses bloom longer, have better disease resistance and stay their described size. There is also the rose rosette issue. Rose rosette is an untreatable plant virus that disfigures plants, and some horticulturists think the increase in roses in the landscape has led to an increase in rose rosette disease in the landscape.

If you have Knock Out roses, there are two things to do that will help with the disease issue and the size issue. Cut them back in the fall and cut them back in the spring. Use hedge trimmers in the fall and concentrate on removing the newest growth. Then, in the spring, cut plants back to about 18 inches and clean up any bad cuts or rough edges from the fall pruning.

The recommendation for fall pruning comes from the idea that the mites who carry the rose rosette disease overwinter in buds on the plant. Removing the newest most tender growth will hopefully remove any opportunistic mites as well. The idea is fairly new to the trade and unproven by research to date, but comes from specialists at Oklahoma State University.

Spring pruning may help with rose rosette control as well, but more importantly it will help with size control. Spring pruning will also keep the plant looking better and it may bloom better.

Other shrub roses to consider are Drift Groundcover Roses, Meidiland Roses, Carefree Roses, and a number of individually named varieties. Look for All America Rose Selection winners and plants that have been on the market for a few years for best bets.

The Knock Out rose was introduced by an amateur rose breeder from Milwaukee named William Radler. His love for roses began when he planted one at the age of 9, and he spent years growing and breeding them before hybridizing the Knock Out. He is responsible for about 20 rose varieties currently on the market in addition to the =Knock Out family of roses.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation. She is the host of “The Garden Show.” Send your gardening questions and feedback to features@ljworld.com.