Dyeing with Medicinal Plants

by Herbal Revolution March 19, 2025

Hi I’m Jackie, and in addition to being an Herbal Rev team member, I’m also a fiber artist and natural dyer. I use plants to dye yarns and fibers and, from time to time, offer workshops on the chemistry of natural dyes. Something really cool about medicinal herbs is that they are also useful dye plants.

I will make a disclaimer here that I try to consider the highest power of a plant before I choose it as a dye plant. Some herbs like St. John’s Wort or Chamomile for example, are a source of color but are also a precious source of medicine and the harvest is so tedious that it makes more sense for it to be used medicinally.  The colors from St. John’s Wort and Chamomile, sometimes yellow, sometimes red, can be made from other plant materials that are not as useful as medicine. So, while there is cross over, I always make sure that there isn’t a better use of a plant besides color.

That being said, there are plenty of plants that are prevalent and abundant enough for both medicine making and color. Some of my favorites are Nettle, Comfrey, Rhubarb leaves, Mint, Goldenrod, Rosemary and Mullein. All of these plants will give colors in the yellow-olive green range. There are also byproducts of Fire Cider production that I’m always keeping an eye out for, such as onion skins and turmeric. 

Dyeing is a science and there are necessary steps in order to be successful at it. In a nutshell, most natural dyes require a pre step called a mordant in order for the color to stick and be colorfast.  A mordant is always metallic in nature, and it works like a magnet, the mordant sticks to the fiber and the color sticks to the mordant. The most common mordant is Alum, and it comes in a powdered form that dissolves easily.  To mordant, the first step is to weigh your fibers. This is called the Weight of Goods (WOG). 

If you are dyeing a skein of yarn that weighs 100g, that is the number you will work off of.  The amount of mordant I use is 12% based on the WOG. So, for our 100g skein, I need 12g of Alum. This is easy to scale up or down. If I were to dye 10 skeins of yarn, (WOG 1000g)  I would still use 12%, which comes to 120g of alum. I also use Cream of Tartar in my mordant recipe, at half the amount of the Alum. So, whatever the Alum comes out to be, use half that amount of Cream of Tartar. The job of Cream of Tartar in the process of dyeing wool is to keep it nice and soft. If you don’t have any, don’t worry about it, just proceed with the Alum. 

Getting Started:

Add your Alum to a big pot of water and stir to dissolve. Then, add your fibers and bring the heat up slowly to 180 degrees. I like to let the yarn cool overnight, but a couple of hours is sufficient.  Once fibers are mordanted they can be stored to dye later, so I usually mordant a large amount of fibers so I can get right to dyeing when I encounter some juicy plants. 

The general rule of dyeing with fresh plant material is100% of the WOG. But, this is very loose and I hardly ever weigh my fresh plants unless it is something I am trying to replicate.

To dye with fresh plants, harvest a good armful and add them to a big pot of water. You can chop them up if they are large, like mullein or comfrey leaves. You are basically making a big decoction, so bring them up to a simmer and hold for an hour or two. You could add the yarn at this point and cook it all together, or you could strain off the plant material and add the yarn to the resulting dye liquor.

Once the yarn is in the dyepot, bring the temperature up to 180. Once it gets to temp, you could leave it in there to cool, which will deepen the color, or you could remove it. There will still be color in the dyepot at this point and if you have more mordanted fiber, you could add it to create a range of shades in the same colorway. When you are done dyeing, rinse the fibers gently and allow to air dry.  Let us know if you try natural dyeing with herbs!

About the Writer: When she's not working at Herbal Rev, Jackie can be found gathering dye plants and dyeing yarn, and offering a workshop from time to time. Follow her dyepots on instagram @forage_color.  

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