Peonies

Question

When the flowering is done, should I cut them off and plant the seeds?

Answer 1

Fall is the best time to cut down your Peony plants, they can be cut down to about 3 inches above the soil.
Peonies will shed their leaves when the weather cools.

Propagating Peonies is done from division.
Here are some links with more information.

https://www.gardeningknowhow.com/ornamental/flowers/peony/peony-care.htm

https://www.gardeningknowhow.com/ornamental/flowers/peony/dividing-peony-plants.htm