None of our tps has ever needed staking.
Garden Treasure is our only intersectional, and it is too young to comment on.
Do you grow hardy hibiscus? They seem well adapted to this climate. We have grown some from seed.

Some large double flowers on my TPs do not look well after a rain. The blooms are too tender... They do not need staking though.

All 5 intersectionals I have bloomed for me this year for the first time. Their stems are stronger, but double flowers (Bartzella, Dancing in the Rain) do flop.

Garden Treasure may be short, but the blooms flop downward for me.

Bartzella does better than GT in this regard - the stems stand up for me.

Kopper Kettle has done good as well. Julia Rose stays up, but it's very similar to Kopper Kettle, but in my opinion, inferior. I gave a big mature Julia Rose away to a friend. Now its spot is taken by Morning Lilac.

daveinohio~ actually I just got hooked on hardy hibiscus last year. I've been hooked on clematis for years. pic of my garden spring 2009.
I just got so tired of the flopping and staking so I removed my herbacious p's to make room for tree p's. I planted 'kinshi' 'hoki' and 'hanakisoi.' can anyone tell me what to expect-
Joe

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Not all herbaceous peonies require staking. One that does exceptionally well in my Nova Scotia garden is Nice Gal.

Edward