I have been allowing oak leaves that naturally collect on my garden to remain through the winter for mulch. In the spring this layer is very dense and doesn't seem to be breaking down. I always remove all the leaves because I have heard disease can over winter in them and some of the plants can't push through the leaf mulch. Am I wasting my time? When I have left some leaves they dry and blow around which detracts from my garden. I really dislike raking them up so I'm hoping someone will tell me I can change my ways.