In order to have it growing through the peony leaves you would have to dig into where your Peony is planted--not a good idea. Peonies do not like to be disturbed. Even though it is not blooming the tubers would be growing and preparing for the next years growth. Your Zinnias roots would be competing with the tubers and wouldn't have much room to grow and settle in.

However the Zinnias would look good planted behind the peony bush. You could grow a small vine like blackeyed susan vine on either side of the peony and train it to climb on the peony bush.

Thank you oilplanter. I thought it might work since they are annuals and I did not dig I just threw the seeds on the soil and they grew. LOL

I have a clematis growing threw the peony but it blooms early. I need something late summer I like your suggestions. Thank you.

The shade of the dahlias during the younger stages of the zinnas' life might not be approriate.