Sawwort is a perennial plant with purple thistle-like flowers and serrated-edged leaves. It produces colours similar to those from weld (Reseda luteola) and, as with weld, the main dye component of sawwort is luteolin. According to Dominique Cardon (Natural Dyes 2007), sawwort has been used in Europe since the Middle Ages, especially in areas where weld was not harvested, and in Tuscany during the 14th and 15th centuries it was as highly regarded as weld.
Sawwort is a dye plant I have wanted to try for a long time but had not been able to find, although it is native to Britain and grows wild here. Recently I discovered a supplier of native wild plants (www.naturescape.co.uk), from whom I bought several sawwort plants last Autumn. Sawwort should not be harvested for dyeing until the second year but as usual I was too impatient to wait until next year, when my plants would have been more mature.
I used about 100% dyestuff to weight of fibres and this produced a dyebath strong enough to enable me to use the same dyebath 3 times for successively paler yellows. The results were very pleasing and I shall probably order more sawwort plants this Autumn, especially as sawwort is a perennial plant and should prove more reliable as a garden plant than weld, which is sometimes not easy to grow. (This year I had no self-seeded weld plants and the seeds I sowed in the Spring germinated but the seedlings failed to develop because of the wet weather and are still no bigger than they were in April.)
The photo below shows, from left to right: alum mordant x 3 samples, alum mordant & iron modifier x 2 samples, alum mordant & copper modifier x 2 samples. The first 3 samples show a range of yellows from (a) the original dyebath, (b) the first exhaust dyebath & (c) the second exhaust dyebath