growing, harvesting and using natural dye plants and other natural dye materials

It is the mordant that adheres to fiber. The dye adheres to the mordant. You maybe able 5o dye without the mordant but it likely will be fugitive.

I've been enjoying the heck out of Sally Pointer's youtube channel, and if you haven't seen it, it's worth checking out. She's doing a number of things relevant to this thread, and has several videos on dying textiles naturally.  https://www.youtube.com/channel/UC5XFNQc8zPWyYGCtvB2l9pA

OMG; I just FOUND this pat of the Permies forum! WOOHOO!!! I havbe wanted to dye fabric and yarn for years with natural dyes!! I am in the right place !

And I am learning about natural mordants here, too; oh my, have I died and gone to  the big dyers plot in the sky?

I have been experimenting with avocado pits and skins on sheep wool.  I chopped up pits and skins and added them to soaked border leicester fleece and kept it on a low simmer for about 24 hours. It came out as a pinkish color with a touch of apricot.
Then, I did 2 pots of soaked merino fleece: to one pot I added pits only, to the other, skins only.  I ended up with a dusty/earthy pink. Very dull, which is not surprising.  Merino fiber has no shine at all.  
Border leicester wool has a touch of shine, just enough to notice a little more richness in color when dyed. The trade-off in this example is that it is not as soft as merino.  On the other hand it is more durable.

Many dyers using avocado simmer the pits/skins in water, strain, and add just the water to the dyebath.   I did not do this because my stove was awaiting repair.  I dye in large stainless steel electric pots (they are meant for water bath canning).  It occurs to me now that I could have simmered the avocado stuff in the big pots first and then strain them out, but I didn’t. Either I was too impatient or too dense. Probably some of both.

Apropos of impatience, each experiment used only 4 or 5 avocados. Now I am collecting skins and pits and adding them to a freezer bag (from what I have read, freezing does not interfere with avocado dye production).  When I get around 20 or so I will try again to see I more dyestuff will give a deeper color. I expect it will.

"'They spread the dyed wool out on a field for several weeks in direct sunlight, then put it in a barn as bedding for their animals before rinsing it out in a stream or river."
I found this fascinating tidbit in the abstract of a research article about a wool rug whose colors are still brilliant after 2500 years. Immediately I thought of the permies fabric and dyeing contingent.
https://www.sciencedaily.com/releases/2021/03/210304133511.htm

WOW...so, they spread it out in the sun for several weeks, to let the sun work it, then  they put it into the barn and used it as bedding. which means the animals slept on it, among other things, then they took it and rinsed everything out of it in the river or stream... then they dyed and spun it, and wove rugs with it.

Interesting! I wish I had a few acres and could have  a few sheep; I would want to experiment with this technique.

Can you share pictures of the colors of the first avocado  dye experiment?

Old thread coming to life thanks to the Dailyish....

This is not an area I've touched on, but on display in the hotel we stayed in the Sacred Valley in Peru in April was this fascinating exhibit of how they dyed their wool (this is the home of alpacas after all).  The lady selling products beside the display saw our interest and showed us the mealy bugs on the cactus pad.  She picked one, then rubbed it to get the whitish stuff off, then crushed it to show a brilliant red.  They get 16 (I think, or was it 18) reds from the mealy bug depending on what they mix it with and use as a fixative.

Thanks for reviving this thread Derek!
That's an excellent display...beautiful colors!

The scotch broom will be in bloom here soon.  The flowers make a very bright yellow.  The greeish shade fades in about a year of indirect light, but the yellow is a similar chemical to the yellow found in weld and has a similar lightfastness to that.