August saw us using Goldenrod (Solidago), Valerian and Dahlias (we used dahlias back in March, I think it was, but they were frozen and we wondered if using them fresh, just as they were beginning to fade and be dead-headed, would make any difference).
The goldenrod and valerian were cut up, soaked in cold water overnight then simmered for about an hour. The dahlia petals, without any other parts of the flowers, were soaked overnight in cold water and, as this produced a lovely red liquid, we heated it only gently and for a shorter length of time.
From left to right: standard colour, modified with acid, modified with alkali, modified with iron and with a copper (rather than alum) mordant:
The fresh dahlias with the frozen ones to the right of each skein. Not very good photographs I'm afraid, the first photograph shows the green shades better but you can see that the frozen dahlia petals produced more brown shades. This is by no means an accurate comparison as the frozen dahlias were also heated for longer...