Question: I have purchased my first home and have room to plant my favorite flower, roses. I need a type of rose that is low maintenance and disease resistant. Someone suggested that I plant Knockout Roses. What are Knock Out Roses?

Answer: William Radler is the horticulturist who spent decades of dedicated breeding and careful selection to develop the Knock Out landscape rose. This type of rose has only been available to the public since 2000.

Originally there was one color selection — bright red — but now they are available in yellow, pale pink and pink with a yellow center. Knock Out landscape roses are the top selling rose bush in the USA.

Knock Out landscape roses are fast-growing, compact, deciduous shrubs that grow well in zones 5-11. They can be grown singly; however, if you want to maximize the beauty of prolific blossoms, plant in groups of three, five or seven. They are commonly planted as a hedge or as a shrub border. The shrubs have dark green, lustrous foliage that lasts into late fall, and blossoms that bloom all summer and don’t require deadheading.

Their blossoms are self-cleaning meaning the old blossoms drop off after they have faded. In the winter, the shrubs go dormant but will produce showy rose hips, a berrylike fruit. One thing to keep in mind is that Knock Out roses do not have much of a fragrance.

The best time to plant Knock Out roses is between late winter and early spring. This gives roots a chance to get established in the landscape before flowering begins and the heat of summer sets in. Annual pruning in late winter is definitely required, since these shrubs can grow 3 feet each season; however, you probably won’t need to prune first-year plants.

It is generally recommended to prune the plant to a height of 24 inches to help develop a desirable form and shape. Cutting them back severely is not recommended. They won’t die but will take a long time to recover.

Also, a little corrective pruning in summer allows each bush to direct more energy to fullness of foliage. Older, declining and broken canes need to be removed when you see them. Correctly pruned plants will produce a flush of flowers during late summer and early fall. It would be beneficial to apply a slow release fertilizer in the late winter.

Knock Out landscape roses need a minimum of six hours of direct sunlight every day. Full sun would be ideal. They will grow in a shadier place but will be sparse with reduced flowering. These roses are quite tolerant of most soils but not poor drainage.

Always thoroughly prepare the planting site (not the planting hole) with liberal amounts of compost prior to planting. A natural mulch is a great way to help reduce weeds and maintain soil moisture. Replenish mulch as needed after pruning and don’t mulch up onto the stems. Mulch the roses with pine bark, hardwood bark, chopped leaves or pine needles.

When watering, avoid wetting plant foliage. A drip irrigation system would be helpful because water is strategically directed to the plant and doesn’t keep the entire bed wet. Knock Out roses are drought tolerant once established, but during the hottest part of summer, will need to be watered.

Knock Out roses are practically immune to the fungal diseases of other roses; therefore, no preventative fungicide spraying is required. Aphids are a common early season pest of roses, but aphids can be easily controlled with an insecticidal soap or horticultural oil. Make sure that you read the label carefully before making a purchase.

As with all varieties of roses, deer love to eat roses and will eat them to the ground if given the opportunity. So keep that in mind as you select a planting location.

I think you will find the Knock Out landscape roses to be the solution to your desire to have something beautiful, low maintenance and disease free.

Do you have a gardening question? Please email the Douglas County Master Gardener Plant Clinic at

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