Q: I have read your recommendation of ‘Knock Out’ rose but didn’t find anything on the proper way to deadhead/prune them. How do you do it?
A: ‘Knock Out’ rose is a plant I can wholeheartedly recommend to any gardener. It blooms so heavily, it is so pest resistant and it is so tough, hardly anyone has a bad experience with it.
Mine has deep red blooms each summer. ‘Double Knock Out’, ‘Blushing Knock Out’ and ‘Pink Knock Out’ are also on the market.
‘Knock Out’ blooms continuously from April thru October if the faded blooms are removed regularly.
I visit mine every week and twist off the faded flower buds. Every four weeks I cut long stems back. This two-step process keeps new growth coming and removes the hormone-filled hips that tell the rose to bloom more slowly.
Remember that your Knock Out will make flowers 16 inches above where you make your summer cuts.
If you want continuous blooming, clip branches 16″ below the level where you want the next flush of flowers
In spring I cut mine to 18″, which is 16″ below the height I want them to flower: about waist high. It is possible to leave them higher than that, depending on how big you want the plants to be later. They can get up to 7 feet tall but look pretty rangy at that size.
NOTE: Knock Out rose does best when fertilized regularly. Apply landscape fertilizer every month.