There are several things you can do to prevent weeds from re-growing.
First, make sure the weeds are pulled before they flower or go to
seed. Many weeds spread by seed.
Second, once an area is fully weeded, apply Caroson, a granular weed
preventative made by Lily Miller (Products for Weed Control, Lily
Miller: http://www.lillymiller.com/weed_control.html#3 ) This product
is perfectly safe to use around established plants, and doesn?t need
to be reapplied constantly. However, the product will prevent plants
from re-seeding, so if you have flowers nearby that you want to re-sow
each year, Caroson is inappropriate.
Another thing that will help is to remove the mulch, then apply pieces
of newspaper to the soil. The newspaper must be only black and white
non-glossy ink, and you should dampen it. Overlap pieces by 6 to 8
inches. Then, apply a thick layer of mulch. The newspaper prevents
light from getting to the weeds, thereby killing them.
You may also find the following articles helpful:
? ?Garden Mulch FAQ,? About.com:
? ?Weed Control Strategies,? Mother Earth News:
? ?Weed Control Facts,? Freeplants.com: