Peony season is coming up - in fact I cut my first peonies yesterday! I have a couple very early single peonies that sometime open as early as the first of May. One is a dark red called 'Early Scout' and the other is a creamy yellow, kind of a beige, called 'Rushlight' (pictured below). 'Early Scout' is a hybrid with the fern leaf peony and is quite short - maybe 18 inches tall. 'Rushlight' is also some kind of hybrid but is about 3 feet tall.
I bought a bunch of very early and late peonies when I started growing cut flowers because I wanted to ensure a full season of bloom. Then I learned that you can store peonies in the fridge for weeks so there is not much point in growing the late ones.
When to Cut
Peonies are supposed to be cut while still in the bud. This is sometimes called the "marshmallow stage" because the bud should feel soft but firm like a marshmallow. This usually is when the color is showing but the petals have not started to open. This phase does not last very long so you need to check every few hours if you want to catch it just right.
There are two advantages to cutting at this time. First, if you put the flowers directly into a vase they will last the longest time because they will be in the vase when they open. If you cut at the right time they usually open the next day.
The second advantage is that you can wrap the the flowers in plastic wrap or a plastic bag and store them in the refridgerator and then bring them out to bloom later. I have held them for more than a month this way. They should be tightly wrapped, but leave a couple inches of the stems exposed. when you want to use the stored peonies, unwrap them and cut a half inch off the stem, place them in water and they should open in a few hours.
How Much to Cut
When cutting peonies, you can either cut about one third of the flowers on the bush and take most of the stem, or you can cut all the flowers if you only take about a 10-12 inch stem. I usually do a few of each. The point is you need to leave enough foliage on the plant to not set it back for the following year.