In the arid environment of the Treasure Valley, applying organic mulch is one of the most beneficial, science-backed practices for tree health. However, improper application is simultaneously one of the leading causes of tree decline. When applied correctly (a 2 to 4-inch layer of organic wood chips extending to the tree’s drip line), mulch dramatically reduces soil moisture evaporation, mitigating the intense summer heat of Canyon and Ada counties. It also insulates the root system against winter freezes and slowly breaks down to introduce organic matter into our heavy clay soils. Unfortunately, the prevalent practice of “volcano mulching”—piling mulch high against the trunk of the tree—is extremely destructive. A tree’s trunk and root flare are designed to be exposed to the air. Burying them in moist mulch suffocates the lenticels (pores used for gas exchange), traps moisture against the bark, and inevitably leads to crown rot and girdling roots. Always ensure the root flare (where the trunk visibly widens at the base) remains completely exposed.