I had several huge flat Italian parsley plants that I pulled up by the roots to harvest and make room for some other plants. I was drying them outside in a box and it was in the 60's with a lot of sun and wind. However, I had to bring the box in because we got rain, and the box was inside for several days. I had put them in the box as-is, roots and everything. When I opened the box I discovered that most of the parsley had turned yellow.

Why did this happen, and how can I prevent it from turning yellow in the future? Was I supposed to cut the roots off?

Also, can the yellow parsley still be dried and used, or is it back to the compost for it?

Thank you.

I think your parsley died instead of dried because the root was still attached .
I dry my herbs in the dark& dry and don't leave the roots on.
If you have access to a car placing the herbs in the back or trunk area will dry them fast usually 2 or 3 days

can't say if the yellow parsley would be any good.

Good luck don't give up Gardening is a lot of trial and error