This is a pic of my Autumn Joy. Each year it gets these spots on it. Is this from excessive heat? They get heat reflecting from the concrete driveway and full sun.

Linda, do you have a real close up of the actual damage?

Jacki...I did the best I could with it being almost dark here. I'm beginning to wonder if mine is true Autumn Joy. I thought it was suppose to be red when it blooms
I did buy my Autumn Joy with a tag included, but I'm not sure that means much....
Maybe you can see these pics better.

It is hard to see. I've had similar damage from water that is too alkaline, or too cold. Do you have pop up sprinklers? Maybe try watering with a drip or soaker hose instead.
I agree, that doesn't really look like AJ, mine has almost salmon coloured blooms, not pink with yellow like this one.

Thanks Jacki....and I do water them myself sometimes with a sprayer, and the water would be cold to them on a very hot day. I need to make note of this so next year I just water them underneath. I'll try to get a really close pic tomorrow.

Mine are a dusty rose color. http://cubits.org/sedumandsemp...

Jumping in here....

First, I do not grow any of the larger sedums myself, but have some I follow in the neighbor's yard. I do have a couple of thoughts to share and an experiment to try.

Some thoughts come to mind 1) Perhaps a portion of your flowers are not visited by pollinators, resulting in a non-fertile seed body area that simply dries up. Try to see if the spot starts after the flower opens and stays open for awhile, or if the spot appears before the flower opens. 2) In areas with intense sun, water on a flower or plant can focus and intensify the sun's heat, resulting in burning. So does your watering routine leave areas of water on the plants when the sun is intense? Do you water in the middle of the day?

Here's an experiment to try. Place a zip lock bag over the flower head before the flower opens. Hold the bag in place with some tied soft thread and zip up as much of the bag as you can. Watch it to see if any spots develop. That may tell up something.

twit....noooo....I do not water during the heat of the day. Either early morning or late afternoon...

I like your thoughts on the pollinators, too. I'll try the ziplock bag experiment and let you know what happens....I'll take some pics before and after.

Linda how did this experiment work out for you?