Also dont go heavy on the fertilizer. My knock out rose bush isnt blooming. The Double Red Knock Out Rose Rosa Radtko Diyvegetablegarden Double Knockout Roses Knockout Roses Knockout Roses Care If you dont deadhead your knockout roses correctly it may develop a blind stem that wont produce any blooms. Knockout roses not blooming . Discussion in Flower Gardening started by gsdruth Apr 24 2012. Of course adding fertilizer will help keep your Knockout roses blooming regularly. The second lady has some of her Knock Out roses in one bed that are not blooming. First Do not overwater. My double knockout rose plant had large beautiful blooms when I first bought it. When you do feed them start with a slow release fertilizer. It was beautiful last. So without further ado lets get started- Whats On the Page show. The first lady had a major storm that obliterated her roses. Several Knock Out rose bushes blooming along a fence line or at the edge of an island landscap...