Organic amendments are added to modify a soil in the zone where roots will grow— unlike mulches, which are applied to the undisturbed soil surface. These materials may be incorporated into landscape soils to improve plant growth. However, research has not shown that adding amendments to planting holes for perennial plants provides a significant advantage compared to using native backfill. Learn which situations may lend themselves to amendments and how to make a choice among the many amendments available.  Includes a table of amendment qualities that quickly breaks down various choices along with their respective benefits and detriments.