[shearbolt]

We use snapshot undermulch and I always am stressed out about the 1/2 inch irrigation window that the label demands. I think it says 3 days but obviously that is when it degrades under the sun.

 

[grassman177]

i cant say how much, but i bet it does help as the mulch is usually wet and may even activate it with mulch alone.

 

[Think Green]

We use Preen ultra under the mulches also. I believe the label requires it! Common Sense wise, it is better to do this as these products work through the soil rather than organic matter. More organic matter in the soil will require more product. It may take more water to get the product to bond with the soil for adequate control.