Mulch in our beds has stuck together. While breaking it up we noticed some of it had turned white underneath. What causes this? Should we take all of it out and remulch? When we moved here we noticed that the beds were pretty high on the foundation. To try to lower the beds we removed all the previous old mulch in some of the beds replacing it with organic bagged compost. Should we put a cedar mulch on top of that? How often should the mulch be replaced...if ever? Thanks for your input.

Cedar or any shredded native tree trimmings would be fine. The white you are seeing is actually beneficial fungus but the fusing can prevent water penetration so it's best to break up the matting with a cultivating tool. Mulch in that condition does need to be removed, certainly not thrown away. Adding some molasses and kicking the bacterial count up will usually solve the problem.

Thanks for replying so quickly. We generally put out the molasses, but we'll be sure it's part of the bed preparation.