Don't know if I'm much help but I got some shaved pine chicken bedding from DD (also in MI) last year. It had been stored in plastic garbage bags for several months before I had the chance to get it and spread it out on the garden last fall. About a month ago, I did a remineralization thing with my main veggie-growing bed (it's a small space with half annuals/perennials/shrubs and half veg). About half of the shavings got mixed into the soil with the minerals. It is early to check for any problems since I just planted peas, carrots and radishes. Could your shavings be too thick, perhaps concentrating the benefits too much? Did you pull the shavings back to expose bare dirt for sowing seed? Perhaps leaving the shavings pulled back until germination occurs would be a help?
