Weld gives yellows and olive greens with the use of iron, and gives the most brilliant emerald greens and teals when overdyed with indigo or Saxon blue.
Weld, reseda luteola, is a biennial plant native to Europe and Asia and has been used for millennia as an important natural dye. Weld gives a very lightfast yellow and has often been over-dyed with indigo to make the most glorious emerald and teal greens that are very lightfast. I have heard it mentioned to be the most lightfast yellow natural dye.
Weld is also known as Dyer’s Weld, Dyer’s Rocket, and Mignonette. I have somewhat thought that weld gives a slightly softer, more buttery yellow than some other sources of yellow, like dyer’s chamomile or goldenrod, which give extremely bright, bold sunny yellows with gusto. I’m not sure if my analysis is entirely true, but it can be true of Weld and certainly if one is using the dried plant to dye with. The fresh and blooming plant with give a bright, bold yellow.
Weld extract gives a bold yellow that I almost feel wants to have a faint hint of chartreuse to it! Note that Weld extract is a sort of chartreuse-ish green powder and I feel like a hint of that color wants to peak out of the bold yellow that it gives.
Weld is a biennial plant that grows a small leafy rosette and long taproot the first year and sends up a tall flowering stalk to produce seeds the 2nd year. Bees really love the flowers stalks. I have found weld to be somewhat challenging to grow in the ground, because it does like a bit of light to germinate and needs to stay moist when germinating and growing. I can see why it has favored growing in English gardens, as their climate is said to be wetter. Because the plant has a single taproot, it doesn’t handle being transplanted as well, but once established, it is very hardy to cold. I did find that my plants did self-seed later in the year when there was a rainy spell, but before that, I can’t noticed any reseeding. So, now I start the seeds in potting soil and make sure to keep it moist while the seeds are germinating!
Weld should be used with a mordant, alum for wool or protein fibers and aluminum acetate or aluminum lactate for cellulose fibers.