When cold weather arrives, gardeners often reach for extra mulch with a simple assumption: if a little insulation is good, a thick blanket must be better. Unfortunately, piling on too much can create its own problems, from trapping excessive moisture to reducing the oxygen reaching plant roots. The ideal winter mulch depth also isn’t identical for every plant, because a newly planted tree, established shrub, and tender perennial have different needs. Research-based recommendations commonly put ordinary landscape mulch around 2 to 4 inches deep, while some plants benefit from a thicker temporary winter layer. Understanding the difference can protect your plants without spending money on bags of mulch you never needed.
