Weekend Gardening: Hit A Home Run With Knock Out Roses

March 25, 2018

by UF/IFAS Extension

Landscape shrub roses will not make you great cut flowers, but they will give your landscape an abundance of rose flowers for the majority of the year. They practically bloom non-stop during the growing season, from March to November in Northwest Florida. Also, they are much less prone to blackspot disease than the traditional hybrid tea, floribunda and grandiflora roses.

The Knock Out family of roses was started by rose breeder Bill Radler when he crossed seedlings of ‘Carefree Beauty’ with ‘Razzle Dazzle’ to create the original Knock Out rose. The family now includes varieties that range from blush to vibrant red and even yellow.

In general, Knock Out roses are drought tolerant, self cleaning, and resistant to black spot and powdery mildew. Since they require little maintenance, they are ideal for gardeners who enjoy roses but who aren’t interested in the upkeep required to grow hybrid tea roses. The only drawback of Knock Out roses is that they don’t have a strong fragrance. According to the Conrad Pyle website, the only true fragrant Knock Out is the yellow ‘Sunny’ cultivar.

Like all roses, Knock Out roses need to be planted where they will receive at least six to eight hours of sun each day. It also helps to have a site with good air movement and well-drained soil that falls between pH 6.0 and pH 6.5.

Knock Out roses generally grow three to five feet tall and equally as wide, but some sources say they can reach eight feet tall if not pruned, so be sure to space them appropriately.

After planting, water them regularly until they get established. Apply a three-inch layer of mulch to help retain moisture in the soil, pulling the mulch back from the stem of the plants. Be sure to avoid overhead watering which can increase the chance of fungal leaf spots. They prefer a deep watering every once in a while rather than frequent light waterings.

Knock Out roses are referred to as self-cleaning meaning that the spent blooms will fall off on their own. They will re-bloom every five to six weeks regardless of your deadheading practices. Deadheading is the removal of faded blooms. Most gardeners have found, however, that occasionally deadheading will create and maintain a tidier, more attractive plant.

For more information on rose pests and diseases, refer to the University of Florida/IFAS online publication at http://edis.ifas.ufl.edu/ep371 or contact your local Extension Office.

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Written by William Reynolds · Filed Under News