Osmocote is great for all roses but I suggest you wait until spring before you add the Osmocote fertilizer around the roses. You live in a cold winter climate and you want the roses to rest or go dormant over the winter. In spring, when you see daffodils in bloom you can apply the Osmocote Plus around the base of each rose plant, scratch it into the soil and water. Then your roses will be slowly fertilized for the next six months. I suspect your Knock Out roses will be a knock out success next summer. Keep growing, Marianne Binetti