Rosa 'Radwhite' White Knock Out Rose. Dark green foliage with single white flowers. Moderate leaf spot resistance. From the creator of Knock Out Rose. Own root. Height: 3-4 ft Width: 3-4 ft Soil Conditions: Moist/Well Drained Flower Color: White Bloom Time: May, Jun, Jul, Aug, Sep. Rosa 'Radwhite' syn. Rosa 'White Knock Out' Rose 'White Knock Out' (Shrub) These hardy deciduous shrubs are hybrids between the species and old roses. They are of informal habit reaching a height and spread of 5 feet. The flowers can be single or semi-double and open flat out.