Unroll the weed mat where you want to install it. Use a utility knife to cut access holes for plants, if you are installing the mat in a garden.
Flatten the weed mat into place so that there are no major creases or folds. Keeping the mat flat will help prevent rodents from getting underneath the mat.
Stake one corner of the weed mat into place by holding the tip against the ground. Tap it with hammer until it embeds in the ground. Next, stake the other corners in the same manner. Finally, stake the edges in 2-foot intervals between the corners.
Add pea gravel or mulch on top of the weed mat. Spread it in an even layer over the top of the mat. Pea gravel is normally used when installing weed mat underneath a patio or walkway. Mulch is commonly used when installing weed mat on a flower garden.