Have you tried dyeing fabric with celery? It works! It's really easy to do, too. I grew celery in my garden this year, so I picked one bunch to dye 3 yards of linen blend fabric. I cut off the root end, which was pretty dirty, and put that part in the compost bin.
Then I chopped up the rest of the stalks and leaves.
I put it in a stock pot and covered the celery with water.
Then I simmered the celery and water for 60 minutes. In the meantime, I made a pizza, which was confusing because the celery made our house smell like soup.
I also presoaked my fabric in an alum bath. I don't think you have to measure exactly for this pre-soak, but the recipe is:
4 Tbsp Alum
3 Tbsp Cream of Tartar
1 pot of water that's large enough for the fabric
Mix the alum, cream of tartar and warm water together. Add wet cloth (just get it wet with plain water first) and heat the pot on low heat to a simmer. Stir the simmering pot periodically for 30 - 40 minutes. Then you can remove the fabric (be careful since it's hot!). You can use the wet fabric right away or dry it to dye later (hang it to dry or put it right in the clothes dryer, depending on your fabric and your preference).
After simmering for an hour, the celery looked pretty wilted.
I removed all the plant material, leaving the liquid in the pot. Then I added the fabric, this white linen blend.
I let it soak overnight at room temperature, and the next day I rinsed it out. It didn't look that yellow, yet.
I dried it on medium heat in the dryer to help set the color. The yellow became a bit deeper. Then I washed it on cold and dried it again, and was happy to see that the color stuck.
But now that it's the beginning of fall, I feel less interested in breezy linen pants. I'm wondering if I should make pretty yellow pillowcases instead.
Or maybe a Lottie dress or a Cabin dress? I can always wear tights with a dress to make them last longer into the fall.