I'm starting a fall project trying to get ready for next spring. I have a front flower bed (just bought the house) that was full of rocks (riverstones). I guess the previous owner had decorative rocks at one time. I'm going to remove the top 4 or 6 inches of this dirt since I cant dig holes to plant anything without hitting rocks. If I then fill this area with a lasagna bed how much will it shrink? I have a front door so I don't want the bed higher than the house. I would like to have it ready for spring next year. I do have a compost bin in the back but going to use that for my veggie garden. I went to the recycle center we have here and can get free truckloads of shredded mulch. The mulch looks like shredded leaves and branches. The mulch pile is high (like fine bark mulch) but around it at the bottom is about a foot of fine mulch that has grey mold when you pick up the layer. I am assuming that would be the best stuff to get. The only green I have is manure from my sisters horses and cows. Not sure which is better, so getting both. Will this work ok to layer these and how high should I build this?