Peonies really like to have winter chill. There are some newer ones that can get by with less, but IMO the lower chill ones still grow better adjacent to where the hardy varieties thrive, and where they get some lower temperatures over the winter months. In zone 9b, peonies may struggle in years when the winters turn out to be warmer than expected, or the chill period is very short.

But I'm not a peony aficionado. I purchased some lower-chill ones for my MIL. She lives in an area that is too warm for the higher chill types, even though she gets occasional, short-lived snows each winter. The lower-chill peonies do fine there. The nurseries sometimes tout the pricey low-chill ones for warm-winter areas of SoCal, but some friends said they survived, more than thrived. YMMV

I love peonies, but have always been advised that they just won't grow well here. I'm in your same zone. Lots of peony style roses that you could do instead... that's what I do! :)

In the shade I also grow the proven winner pink double azaleas and it gives me my fix for frilly flowers as well. :)

Here's the proven winner promo video for it... I have to say I really do love this azalea for the shade! https://youtu.be/9NTB0cA2OAQ

Thanks guys! it seems that they were able to get the winter chill (it gets down to 40s here for a few days in the winter). It's the summer heat that seems to be a problem, or maybe too early a spring, I'm not sure. The ones I have right now are sarah bernhardt and a white one that a friend sent from the midwest. I 've never heard of double azaleas! that's awesome! I also wanted to switch maybe to david austin roses, but I already have so many roses ^^'

I think you can cheat a little. Get several big bags of ice and dump it over where they are planted one chilly night in January. Then put some mulch over it to insulate so the ice stays longer. I did that for some bulbs and it worked. It's work but hey for peonies it might be worth getting a pickup truck bed of snow one day just before sunset and drive it home to put over the plants. I used to put pots in a florists friends refrigerator and that worked very well for tulips and hyacinths.

I'm off for an errand, so cannot be too detailed now. But it is not as simple as how low the temperature gets--it also requires the chill for a required number of hours. For some fruit trees, for example, they are listed as needing 600 hours, or 1000 hours. The additional problem some CA zones encounter is that we can get irregular warming periods during winter. So the chill period is broken up by warm weather, followed by more chill. This can work nicely for some trees that will bloom multiple times (after the temperature "trigger"). It does not work so well with plants that want a block period of chill.

I am in a hot inland valley, 9b. Some folks living near my parents have beautiful Peonies. They perform well. I asked once what the variety was and she replied that they were there when they bought the home. Previous owner must have known a low chill variety. It is a massing of all the same Peony.

It is interesting that you mention the summer heat. I swear her's were dormant and gone by summer.

hmmm thanks guys!

It doesn't seem like the chill is an issue because it does get cold here, and the icing has worked somewhat before. Although, like user gyr_falcon mentioned, it gets intermittently cold and warm... my issue seems to be either the early warmth of spring or the heat of the summer. They stopped growing very early in the season and reached less than 5in height. I'm not seeing a bud anymore; it must've gotten burned last summer. The type is the Sarah Bernhardt type, which apparently is low-chill. Question is: should I leave the tubers alone in the ground and hope new eyes grow this coming spring (with the same icing ritual)? or pot them in the shade or forget it altogether? :-/

With USDA zones can be somewhat unhelpful at times. The zones seem to go by frost dates, so two diff places can have the same zones, same frost dates, but the amount of heat received can be quite different. And the heat makes a big difference when selecting plants!

Actually, the USDA zones are based on the average annual minimum winter temperature. They are not nearly as useful as the Sunset zones. That is why, even when we worked nationally, we always used the Sunset zones and information. It was a real shame the National Book and Sunset system did not catch on with the rest of the US.

Ahhh that makes better sense...