This is the new 2017 crop.
Genista Tinctoria iss grown in my dye garden in North Wales where I have had it for ten years. Despite the fact that it is said to be a weaker dye than Weld mine has grown stronger the longer I have had it.
The dye in Dyers Greenweed is luteolin the same as in weld ( Reseda Luteola) and in France in the 17th century it was numbered amongst the five yellow days considered colour fast enough to be used in high quality dyeing.
Seeds and debris of it have been found in archeolgical sites in York (9th-11 century) and Bristol (13th-14th) century.
( Dominque Cardon Natural Dyes).
Soak the dried plant material overnight allowing 100g for each 50g of fibres. Heat to a simmer before allowing to cool. Extract the liquid, re-enter the plant material tied up in a muslin bag along with premordanted fibres. Heat and maintain just under a simmer for one hour before allowing to cool. Do not boil for prolonged periods as this can dull the dye. Add a dash of ammonia or stale urine for a bright yellow. If you leave dye stufff soaking for a further four or five days you get a significantly better colour.