We've recently moved to middle Tennessee and I've inherited about 15 knockout roses. Right now they are about 4 ft high. I know that I need to trim them way back (I was told to about 10" high), but I'm not sure when to do it.
you can do it now. I personally would not cut mine back 10inches from the ground. Mine is about 5 feet tall and on my to do list. I'll cut it back about 1/3. I also have tree formed mine, so I cut off any stray branches that grew over the last season. Also, don't put mulch up on the trunks, they don't like this!
"In the spring, at the end of the day, you should smell like dirt"
Posts: 1058 | Location: North MIssissippi zone 7 | Registered: Jul 13, 2004
Ruby is closer to you than I am, but I always wait until the forsythia blooms or close...same for other roses too. I do cut mine to about 12"-18" each spring but I also have to trim during summer too to keep them in bounds. That is about all the care the knockouts require all year! Some times I'll throw some alfalfa pellets around them to act as a slow release mild fertilizer.
"The soil is the source of life, creativity, culture and real independence." David Ben-Gurion
These are awesome rose bushes. They can be pruned to that recommended height of 10-12".
Not knowing your growing conditions, you may find they need very little attention. Research them online. Then ask your local gardener - good test case to find which nursery really knows their business.
I'd imagine in Tennessee your spring is well along by now and its time to remove your winter protection from roses and prune them back. Shrub roses are pruned like other roses. When the leaf buds are beginning to swell, but before the buds break, you can begin to prune back what is damaged, dead or otherwise not letting the plant grow as you wish--such as branches crossing another. Knock outs can be cut back to about 10" or...they can be allowed to grow on without pruning. It all depends on how you wish to grow the rosebush--if its to be a compact bush, then cut it back, if you'd rather let it grow more as a bush, then you can just clean it up and do no major pruning.
Some prefer to let young rose bushes alone the first couple years--others treat the 2nd year like any other.
If you don't prune knockouts at least "some" every year, they get scraggly looking and bare in the middle! There are many that were planted at businesses around here and that is what they now look like cause the "yard man" doesn't know how to care for them!
"The soil is the source of life, creativity, culture and real independence." David Ben-Gurion
