Is there a "best before" date for leaves to be used as rhododendron mulch? If I have a large pile of leaves that have been slowly composting in a pile since last year and use that almost-rotted material now on my rhodos, will a significant portion of the nutrients from the leaves have already left and have been wasted on the soil under the pile, or will the leaves still add significantly to my rhodos over the winter?
Main value of mulch is insulation. Rhododendron roots need lots of air, do not cover them with wet or compacted material.
