It makes my back ache just looking at trying to turn those piles. I just ordered my 2015 Preen supply. 31# for $59 with postage paid. I still have about half of what I had last year but I didn't put it out over the entire garden this last summer. Next year I will hit the garden hard with a preemptive strike. lol. I will get ahead of the weeds one way or the other. I even put preen on top of the wood chip paths to prevent seeds from landing there and sprouting. Although those are easy to pull. It is the ones that come from roots that never die that drive me nuts. Even covering them with mulch only slightly slows them down.
Correction, it was $50.99