Natural dying with purple reed flowers?

I tried natural dyeing today with purple reed flowers.  I soaked them in water in the sun for a week, pouring hot tap water over them to start. I was scared to use boiling water, as it was in a glass jar.  I used the tops of the plants and the water was dark marroon when I poured it in the dyepan.  I used a small skein of homespun cormo I believe, I washed and soaked it first.  After 2 hours the skein was a tan.  It started off stark white.  After 2 hours I added some vinegar, I didnt see much change and the dye water was still marroon. So I sprinkled baking alum on the skein.  This turned the dye water cloudy and the skein did get darker, I kept it on the stove for another hour or so but finally gave up, and put the pot on the porch. I will check it in the morning.  At no time did the water get over simmering.  Mostly it was just below simmering.  I have no reason to think these flowers would dye other than the color of the dye water, I cannot really find any info about dyeing with these. I suppose I should start with documented colors like goldenrod and indigo to make sure I know what I am doing.  I have a big jar of milkweed flowers/plant tops soaking now.  Will be a week tomorrow.