We had 1-acre out of a 10-acre restorative prairie in Central Indiana - sizes are guesses. We had very old thistle -flowering and fluffy - but it wasn't mature. In fact it was very naughty.
We were using wood chips and compost to improve the soil, hoes, sickles and weedwhackers to fight the weeds and only tilled/mowed lightly.
We talked with the prairie experts who said chemicals, lots and lots of chemicals. But we were a no chemical community garden.
Two large plots were completely overrun and that is where we mowed low and double-tarped for a year. We still had runners reaching for the sun.
We started using cover crops on the active plots in the fall and noticed a lot less thistle pressure throughout.
Somebody suggested using them (buckwheat and peas) the next spring on some fallow, weed-infested plots.
Picture knee-high, lawn thickness weeds - no bare patches to start with.
It looked like somebody put thistle in our spreader instead of alfalfa.
By the time the buckwheat flowered, most of the thistle was gone.
At this point we had a thistle or other unwanted weed every ten feet or so but we were amazed at the difference.
This was a one-off experiment and we never did plant the main area. It was our seventh year and it seems like most non-profits get the 7-year itch.
If my memory serves (and it might not) we sowed about twice the recommended amount.
Partly because we hated the thistle but also because that is what we had leftover from fall.
I don't think we had any inoculate (?) for the peas either.
Again, this was several years ago and I am recalling the best I can. I do know that I hate thistle and the buckwheat/pea mix almost eliminated it in one season.
Hopefully, it can work for others.