digging up old roots/replanting
 

I bought my home 18 months ago. I didn't like some of the roses and pulled
them out. I've dug about 2 feet into the ground and the roots are still
strong.
The new rose bushes I'm putting in obviously don't won't have roots that
strong for years. Won't the roots from the old bushes shrivel up and die?
Is there anything else I can do before I drop the new bushes in?

Thanks