I live in Zone 7. I have a Knockout rose bush that has bloomed every year except this one. I trimmed it in May, not sure if I was trimming it correctly with hedge clippers. Now it is not blomming. I put Holley Tone at the drip line and watered it July 31, 2012, hoping this will help; should I just dig it up ? I used to have loads of blooms on this bush, and it is only 3 or 4 years old.
The Gardener’s Answer
Hello, Althea in North Carolina: Is the foliage on your rose still green? If so then there are a couple reasons why it is not blooming, but if the foliage is brown and crispy then go ahead and dig it up. Hopefully it is still green and the lack of blooms are due to the time you pruned or used too much fertilizer. Since this is an established plant and has bloomed in the past we know it is receiving adequate sunlight. This is usually the reason for roses not blooming. As far as pruning your rose, the best time to do this chore is late winter/early spring, while they are dormant and before new growth begins. Pruning to remove dead, diseased, or crossing canes should be done as soon as you notice them no matter what time of the year. It is best not to remove more than one-third of the size of the rose each season. If you pruned more than this I would suspect this to be the reason for the lack of blooms. When pruning you want to make your cuts are flush to the nearest intersecting branch so there are no stubs. Since you pruned in May it could be that you actually removed potential flower buds and the plant has not had time to recover and produce more. Knockout roses are typically prolific bloomers but if given too much fertilizer, this can have the reverse effect of what we are looking for. Too much food can stop your roses from blooming. This is why it is so important to follow recommended application rates for any product that you apply. For now, make sure your rose is getting sufficient moisture, avoid feeding, and wait to see if it recovers.