Hallo ich bin jetzt in der Blütezeit und wollte m...

Severe lack of phosphorous perhaps...........but without a diary and/or a lot more info about what you may or may not be doing, giving meaningful answers is nearly impossible.

Either your soil is too hot or your lacking some nutrients. I used to run in to this problem almost every grow when I would go into flowering, I come to the conclusion that my base water was soft water and 50ppm so there is not enough calcium and magnesium in my base water. Now I use calmag from start to finish and plants are always healthy in flower 99% of the time until I stop watering.