Rosa 'RADrazz' (Knock Out®)

Rosa 'RADrazz' (Knock Out®) was bred by William J. Radler in the United States and is a cross between two Rosa that are used for breeding stock only. It was patented on April 10, 2001 and has patent number PP11,836. It is a shrub rose has the coveted designation of being an Earth-Kind® Rose, meaning it has superior disease resistance and is an excellent landscape plant.

At Brookgreen Gardens, we have been continually impressed by how Rosa 'RADrazz' (Knock Out®) has performed. We have found this rose to show very little signs or problems with black spot (Diplocarpon rosae) or other fungal problems. The flowering is consistent and highly attractive, the shrub is generally full with leaves, and is overall a strong performer and great addition to the landscape.

Black spot can cause leaves to develop black spots with blurred edges, yellowing leaves, and eventually partial or entire defoliation. While black spot is rarely fatal, it can weaken the rose by reducing its leaves and therefore its ability to photosynthesize. Although similar in appearance to cercospora leaf spot, black spot can be distinguished by the less defined and more feathered edges of the spots. As with many fungal problems, issues are generally worse in areas with high humidity. Black spot can be treated chemically. 

Part of our maintenance practice for these plants includes the removal of about a third of the older, woodier stems from the plant in order to encourage vigorous new growth, as well as standard winter pruning and deadheading throughout the season. It has been our experience that, despite the low maintenance stigma attached to these roses, they do perform even better when maintained in a similar fashion as other roses.