How to Dye Yarn with Cosmos Flowers

Materials & tools you'll need

Step 1 — Scour and pre-mordant the yarn

Before any dye touches your fiber, scour it to remove oils and dirt so the dye can adhere evenly. For cotton, wash it with washing soda; for linen and wool, dish soap is the gentler and more appropriate choice. Once scoured, pre-mordant the yarn by treating it with alum, cream of tartar, and an iron water solution. This step helps the dye bond to the fibers so the color takes properly and lasts once the yarn is dry and in use.

Step 2 — Prepare the dye pot

For this project, use a pot that has picked up an iron stain over time — even scrubbing with baking soda and a magic eraser won't fully remove it, and that residual iron becomes part of the dye chemistry. Add fresh Cosmos flowers and marigolds to the pot, then heat on high until the mixture starts to simmer. Once simmering, reduce the heat to low and let the flowers release their color into the water.

Step 3 — Dye the yarn and eyelet cotton

After the dye bath has simmered for about an hour, remove some yarn from the pre-mordant pot and place it directly into the dye bath while it's still warm. The iron mordant reacts with the Cosmos dye to produce a beige-orange color rather than a bright, clear orange. In this batch, white eyelet cotton fabric is added alongside the yarn to see how a woven cotton fabric takes up the same dye. Leave both the yarn and the fabric in the bath for another hour.

Step 4 — Rinse and add more items to the bath

Once you're happy with the color, remove the yarn from the dye bath and rinse it under hot water at the sink. Fill a bowl with hot water and dip the yarn into it for a thorough second rinse, then set the dyed yarn aside. Return the pot to the stove and add an orangey-brown piece of fabric along with more white 100% cotton fabric to the same dye bath for another hour. The dye water should stay fairly clear even as these new items pick up color.

Step 5 — Remove and dry the dyed items

When each item has reached the color you want, lift it out of the dye bath and place it in a colander to let the excess water drain off. Once the items are no longer dripping heavily, move them outside to finish drying. Drying outdoors in open air helps the colors set and gives you a true sense of the finished shade once everything is fully dry.

Step 6 — Compare against other natural dyes

To see how Cosmos flowers stack up against other natural dye sources, prepare a separate mixture using onion skins and marigolds, another using avocado skins, and another using goldenrod. These combinations each produce their own distinct, attractive colors. Lay the results side by side with your Cosmos-dyed pieces to compare tones — the eyelet cotton in particular takes on a coffee-stained look that pairs beautifully with the beige-orange yarn. Check on any fabric still in the dye pot before it finishes, as color can continue to shift toward a greenish-brown the longer it sits.

Frequently asked questions

What is the purpose of scouring yarn before dyeing it with Cosmos flowers?
Scouring removes any oils or dirt from the yarn so the dye can adhere evenly. For cotton, use washing soda; for linen and wool, dish soap works well.

What is pre-mordanting in yarn dyeing with Cosmos flowers?
Pre-mordanting treats the yarn with alum, cream of tartar, and an iron water solution before dyeing. This helps the dye bond to the yarn fibers so the color takes and holds better.

Does the pot you dye in affect the color of the yarn?
Yes. A pot with an iron stain acts as an iron mordant during the dye bath, shifting the resulting color toward a beige-orange tone rather than the color the Cosmos flowers alone would produce.

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