| Mulch Mulch keeps the soil cool in summer, controls weeds, and adds nutrients and organic matter as it decomposes (if you use organic mulch). In early spring, as soon as the ground has warmed up, spread 5 to 7.5 cm (2 to 3 inches) of organic mulch (dead leaves that have been shredded, cedar mulch, buckwheat hulls, etc.) between the plants, adding to it as necessary to maintain this level. In the case of alpine plants, use an inorganic mulch as fine gravel |