While days are still mild, and sometimes cooled by fog, take the time to add a fresh layer of mulch to growing grounds. Mulch is critical to plant health in the hot months ahead since it keeps roots cool and slows water evaporation from moist soil. It also is key to soil health because, as it decomposes, it replaces quickly depleted organic matter. Not all mulches are equally beneficial. Some, like sawdust, actually pull nitrogen from soils. Get shredded wood instead, the kind some tree trimmers will give for free. Compost also can be used as mulch. Dig some into the soil and then pile on more until there’s three inches on top of the bare soil (or last year’s mulch). Avoid putting mulch/compost up against tree trunks or the base of plants since it can cause rot and other problems. Also adjust irrigation to be certain water is penetrating the mulch to reach the soil and plant roots below.