rhododendron flower dye

I used these rhododendron flowers:

I got this gorgeous golden color:

I covered the flowers with rain water and let soak for about a week. I then put them in my aluminum dye pot and added 1 quart of water and 1/2 cup of vinegar and boiled for 30 minutes. I strained the liquid and put it back in the aluminum dye pot. I simmered my wool for 30 minutes and let it cool down before removing it. I let it dry before washing. After washing it and letting it dry again I carded it into this batt. I will do a light fast test as soon as I spin it. I have a larger batch of flowers soaking now(they have been soaking for about 3 weeks now). I will do some more experiments with them soon.
UPDATE:The batch that I soaked for about a month produced less color than the batch I soaked for 1 week.