I agree with decompaction and removing the entire thistle root.
When you say "rock", do you mean largeish ones, or pebbly 'rock mulch'?
If they're large, that's simple. If it's mulch, it's a total pain!
Assuming it's rocks, I'd:
take up the rocks and
decide which plants can be dug and replaced, need to be left, etc
fork the area over, removing all thistle roots
Spread chipped tree mulch/bark mulch thickly (at least three inches)
Nestle rocks naturalistically back into mulch
dig into
native soil and replant
I strongly suggest avoiding salt- it moves freely through the soil and is very hard on desirable as well as weed plants.