It depends upon the weed. A lot of weeds depend upon a first mover advantage of sorts to gain height, so they’re all-in on reaching that height. If you cut them

It depends upon the weed. A lot of weeds depend upon a first mover advantage of sorts to gain height, so they’re all-in on reaching that height. If you cut them, they lack reserves to regrow or the flexibility to branch out etc. That’s why mowing your yard is so effective at keeping weeds down. I live in a desert part of Colorado, and for my yard I find simply watering heavily is enough to kill most weeds because they’re evolved to drink all they can when they can.