Hollyhock is native to Asia and Europe and is a member of the mallow family (Malvaceae). The popular ‘Nigra’ variety has maroon-black flowers. The fresh or dried petals of this variety can be heated in water with alum mordant to make a purple dye. When tin mordant is added to the dye with a small amount of chalk it makes a pale blue, whilst alum with chalk makes a grey-green. Hollyhocks are vigorous and easy to grow, making them a good place to start if you want to grow dye plants.