Could be all the stuff you are spraying on it....

Your treating for insects that it doesn't seem to have. I see no insect damage on the foliage or buds.

Go outside tonight, after it's been dark for a while, to look for insects.

I don't think it's anything that I've sprayed on it, as the permethrin I sprayed *after* this already started to happen, and the neem and soap I used last summer without issue.

Neem can burn leaves and petals.

Why are you spraying your clematis?

I've burned new growth with neem

there is no reason to spray when you don't have insect damage. Except for a few systemic insecticides, they are all contact insecticides that must hit the bug to kill it. They don't prevent infestation.

I'm spraying it because I've previously had bad problems with bugs eating the leaves. From what I've read about neem oil, it is preventative in that it effects the bugs when they eat the plant....?

I'm not spraying it every day; only about every two weeks, and it's very diluted.

I did some googling and I saw some very similar-looking photos from earwig damage, which fits with it only happening during the night, and only being on the flowers.

Here is a link that might be useful: Earwig Clematis damage

It does not look like earwig damage to me. Earwigs make holes, not scorching and color changing.

This is {{gwi:595009}}.

Neem is not a systemic. It does not enter the plants system to kill the bug when it takes a bite.

You do not have earwig damage.

This is earwig damage:

{{gwi:595012}}

{{gwi:595013}}

{{gwi:595014}}

{{gwi:595015}}