Question
I am currently living in the Washington D.C. area.  I recently moved from Virginia Beach, VA where I had huge, healthy, fast-growing, constant-flowering knock-out roses.  I am having a different experience with knockout roses in my new home.

I planted 5 knock-outs in April at my new D.C. home, and I have noticed that they are growing very slowly.  They flowered profusely at the beginning of May.  I have not seen any new red growth on any of the plants, nor does it appear that they have changed in size since April.  The existing leaves do appear healthy and green.  I just removed the dead-heads left from the early-May blooms, and am hoping this will stimulate new growth.

1.  In my current zone (Washington, D.C.), is it too much to expect flowering and growth at the same time?  
2.  Will the removal of the deadheads allow the plant to focus energy on growth?  
3.  Is slow (no) growth symptomatic of another problem (inadequate light or water)?

Thank you!
Tricia

Answer
The winter usually decides when a rose starts into new growth plus when the soil starts heating up. Roses have to really shut down if the winter has been very cold and if the spring is also cold, then that too will delay any growth. Dead heading should be done all summer as when the rose makes a rose that is the end of it's duty. Taking off the old flower heads, encourages the rose to make another bloom. And to make another bloom it has to make new growth. Slow growth is due to the roots. When a rose is transplanted even when it is in a pot, the thin, frail feeder roots are damaged. And the rose won't start into any new growth until the roots repair themselves. Your roses sound okay to me.  Hope this helps.