Whenever we go to our lottie on a Sunny day we take our tortoises with us, put them inside a wooden movable pen wherever the weeds are growing (where no crops have been planted/or before potatoes are up). we give them some shade with a piece of sacking over part of the pen and give them water.
After a few hours the weed population is dessimated... and we have happy tortoises. Anyone else use an unusual method?