1. The Knock Out Rose Before Knock Out came along, who would have guessed a rose would become the most important plant for garden retail? David Austin Roses had made some progress in erasing roses’ reputation as fussy and unattractive garden shrubs. But The Knock Out Rose debuted and gained a reputation as indestructible in just about all climates. It was the highest grossing plant for many retailers for several years. Other varieties in the series have had success, but nothing like the phenomenon of that first Knock Out.