Knock Out Roses
Forget the fussy cultivars, or varieties of plants selected for specific traits, that need to be sprayed with chemicals every week. Rose enthusiast William J. Radler worked for decades to hybridize a rose that doesn't need continuous care. The rose he patented as Rosa hybrida "Radrazz" was offered commercially as the "Knock Out Rose" in 2000. A cherry-red, ever-blooming shrub rose with 5-11 petals, it was named the All-American Rose Selection for that year and has remained popular ever since [source: All-America Rose Selections]. In addition to disease resistance, Knock Out roses show tolerance for an array of adverse conditions, including heat and cold, drought and humidity, and hours of daily shade.
A group of Texas A&M University horticulturists put 116 rose varieties to the test under minimal-care conditions -- no pesticides, no fertilizers and no supplemental irrigation after establishment. At the end of the three-year study, Knock Out came out on top, earning high ratings for appearance, vigor and black spot resistance [source: Mackay].
What's short on stature and long on bloom? Find out on the next page.