Knock Out Roses a shrub to consider

Roses are a good shrub for Colorado. The amount of sun is perfect. However, over other varieties of roses, there are few roses, other than shrub roses that require some kind of daily care. Picking dead leaves off the ground, scratching weeds from around the rose, deadheading and checking for watering is standard maintenance for any rose. Knock Out Roses will save some daily maintenance, that of deadheading spent blooms. Why? Knock Out Roses will form new buds every five to six weeks. If you want more new buds, you can prune. However, Knock Out Roses are designed to be easy care and “self-cleaning.” The rose petals just fall cleanly off and do not produce a seed pod called a rose hip.

Do they need pruning at all? Yes, but timing is everything, even with pruning. Do not start pruning too early in the spring. Wait until the leaves bud out. Do not prune in late summer or early fall. Pruning encourages new growth. Every time you prune, auxins are initiated. They are a hormone which tells the stem below what was pruned to start growing. Pruning in the fall will encourage new growth that is tender. This tender growth will not harden off in time for winter. This means that the new growth will freeze. The rose has put a lot of energy into the new growth.

Knock Out Roses will grow to 3 to 4 feet wide by 3 to 4 feet high each season. The recommendation to prune the Knock Out Roses to 12 inches tall and by the end of the season they will be 3 to 4 feet wide and high. That really depends on the kind of growing season we have here and the elevation in Colorado. You can prune them to whatever width and height you want and keep them at that size each season.

These roses like a location with at least six hours of sun. They need some winter protection. They do not like being in open exposed areas in the winter time. Purchase some burlap and some stakes and just wrap that around the rose. This will help with the wind exposure and keep the roses insulated.

Knock Out Roses come in a variety of colors from pink to pinkish red, yellow and white. There are no true red varieties. There are about seven varieties to choose to add to your landscape. The “Blushing Knock Out” Rose (Rosa x “Radyod”) is a bright pink against green leaves. All in all any color of Knock Out Roses is striking. This is thanks to William Radler whose passion was breeding roses. It was his hobby. In 1992, he did become a full-time rose breeder. He also went onto get his degree in landscape architecture and became director of Boerner Botanic Gardens.

The only problem with Knock Out Roses is Rose Rosette Disease. There is no cure, yet. The virus called Emaravirus species is spread by an eriophyid mite. This is a microscopic mite that causes a stress condition called Witches’ Broom. The Witches’ Broom causes a deformity in the rose that looks like a group of tiny branches or stems growing from one point. It looks like a broom. With Knock Out Roses becoming so popular, maybe a cure is just around the corner. In fending off any disease, keep your Knock Out Roses out of stress.

The best way to keep Knock Out Roses healthy is to plant them in full sun in well-drained and fertile soil. Fertilizing them every five to six weeks which follows the bloom cycle. As mid-August approaches, stop fertilizing them because if you end up with tender new growth as the weather turns cooler in the fall, this may freeze. This would be a lot of wasted energy for the plant.