Dahlia Buds and Blooms Browning

Hello! I have a Kelvin Floodlight dinner plate variety that was doing great with nice buds. About two weeks after I put it in the ground, the buds starting getting this dark brown black spotting on it. Now that the buds have opened, they are beautiful, except the petals in certain patches are browning. The leaves and other parts of plants are not affected. Only the buds and blooms. I have a raised bed about 2-2.5 feet high and water deeply 2x/week. I give it an extra zap of water when it is extra hot out. I live in Northern California. I have pictures at home to post if that would help. Please help. I have gone to two nurseries for help and no one has been able to provide solutions. My other two Dahilas are thriving in same bed on same water schedule. THANK YOU FOR YOUR INPUT!

Do you have an extension agency from one of your local colleges? They should be able to help you if you take one or a picture down to them. I am wondering if maybe you are watering too much? I have had dahlias that wilted down during the day from the sun, even tho they had to have enough water, and then in the evening after the sun went down they would perk back up. But that doesn't sound like your problem. Do they get enough sun?

I think a Master Gardener or the extension office I suggested would be your best bet. You can also write to the Dahlia Society and ask them. Just email them.

Thank you, Jnette! I will check with the resources you suggested.

Both nurseries did mention over watering or underwatering, but could not help me identify how I would be able to pinpoint if that is truly the problem. One even said I should dig up around the tuber to see if its getting too much moisture. Won't that hurt plant if I start digging up around it?

I do have clay soil, so maybe I did not amend it well enough to ensure the best drainage. I thought having a raised bed would alleviate that concern.

I will try backing off the water for now and see if the new buds look better. *Fingers crossed*

If you have clay soil, that really could be overwatering. No drainage. I would try that first, just hold off on it.

Here are some photos

Boy, that is ugly. I would hold off on so much water. Not meaning to let them dry up. And while you are doing that, send a post to the dahlia society, and also see if you don't have an extension service in your area. Jen

I am holding off water to 1x/week and see how it goes. My other Dahila plant which was thriving is starting to get the same looking buds. YIKES. I will cut the watering down for the other dahlia plants as well. THANKS.

Be careful, it depends on how hot your weather is. But, taking your clay soil into account, you might have to be careful. I have to put mine in containers on my deck. Because they have to be dug and I can't dig them. But, that is easier than digging. I had surgery not long ago so no gardening outside for me. Just deck containers.