The thing about peonies is that they will dip over and fall to the ground if there is a hint of wind or rain in your garden. Those blooms do not have to go to waste though. Your first layer of defense is to pick those blooms and see if they will stand up straight in a vase for an arrangement. Oftentimes, the night after a rain, those peonies will be just fine for flower arrangements.
However, if the blooms are too far gone to work well or a bouquet, they are still perfect for mulch.
What? Mulch? Mulch is made from things like wood chips right?
Well, yes, but technically mulch is any organic material that will smother weeds and add organic material to your soil.
Flower petals can do both -- especially if they are in mass amounts as in the bombastic blooms of a peony. Here is how it looks. Simply gather all of the flower petals into a large bucket.
Then take all of those petals and cover the soil around he base of the plants.
Be sure to still allow the soil to dry out between watering, so fungus gnats don't go crazy.
This time of year is typically before any outdoor pests break dormancy. So there shouldn't be a large risk of bringing any pests inside this time of year. If you are nervous about that, you can always just add the mulch to outdoor containers, or in garden beds around your house outside.
Peonies to start breaking ground before most other plants in early spring, depending on how far south you are. Stay off of the ground where your peonies are growing as long as possible to preserve all the good the snow has done for the soil over the winter. So if you decide to spread the petals around your garden beds, be aware of where you are stepping and packing in the soil.
Once the flower petals start to die off. You can either mix them in with the potting soil, or apply a fresh layer of mulch over the top of the petals. It will add a great deal of organic material that will break down in the soil and add nutrients back for other plants.