Rosa 'Radral'

Summary

South Coast Research & Extension Center (South Coast REC/SCREC) is located in Irvine California, this site has a sandy loam soil and plants are irrigated with reclaimed water. UC Davis is located in Davis, California, this site has a silty clay loam soil and plants are irrigated with potable water. More information about the field sites is located in the Nuts & Bolts section.

Coral Knock Out^® is a medium-sized shrub rose with generally uniform habit. In both Davis and Irvine, the foliage on this rose was unacceptable in appearance and health from spring through fall, unlike other roses we have evaluated in the Knock Out^® series. It was affected by both black spot and thrips damage yielding plants without good leaf coverage. In Davis, leaves on some plants wilted frequently on all irrigation treatments during the hottest part of the summer. Coral Knock Out^® put on a nice flush of bright coral-orange blooms in April and May in Irvine. The first bloom was more modest in Davis and dead brown petals hung on the plant rather long before self-cleaning, giving the plants a messy appearance much of the season. In both locations, many plants had significant leaf loss by September due to the combined stresses of disease, heat, and in Irvine, reclaimed water. Because of the serious foliage issues, we would not recommend Coral Knock Out in either the hot inland valley or coastal regions of California.

Rosa 'Radral' Coral Knock Out® on medium water at South Coast REC in August 2020. Photo: D Martinez