Preen is a pre-emergent, so don't use it on any beds where you will be starting veggies from seed.

Lots of weed seeds in horse/cow poop!! Some of the weed matting is designed to be used under mulch. Other types are designed to be exposed. I'm guessing that it's letting light thru, and is the type of weed block that is supposed to be used under mulch.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).