I am in the process of extracting the dye from the current 2017 crop of Golden Rod (Solidago canadensis.
Golden Rod is one of the most lightfast yellow dyes containing the chemical Quercitin and Iso quercitrin but much of the colour is lost on drying. So I have made a concentrated liquid extract from the plants in my dye garden , tested it by leaving the extract for a year and exposing the dyed fibres to north facing light for one month with excellent result.
175 ml of liquid extract will dye 175g of premordanted wool and cotton a rich soft yellow with a slight green cast . Overdyed in indigo it makes a rich green.
Please note the jar shown has been replaced with another type of jar.