When used as sheet mulch, the paper material blocks the weeds' access to the natural resources it needs to thrive. It is a simple hack that won't harm your crops.
"Cardboard will break down over time, but it lasts long enough to suffocate weeds and keep seeds from germinating by preventing access to the sun," Selvey told House Digest.
"Not only does it not harm beneficial insects, but it attracts earthworms to the surface since they love the dark, cool environment this process creates," Selvey said.