September

“False Fall.” That is how I have come to identify September and early October in the Bay Area. The weather cools from the August heat, and ornamental trees, away from their native habitats, begin to turn color but look washed out, and we start to unpack our warmer clothing. There are a few challenges with our false fall. The cooler weather encourages people to water less when we still have not had adequate rainfall, if any. That fall color in trees might be a sign of drought stress causing early dormancy, so supplemental irrigation continues to be needed. When trees turn color too early, their autumnal display can wither when the Diablo Winds (NorCal) or Santa Ana Winds (SoCal) whip up their arid gales, also our most vulnerable wildfire season.
Keeping our ornamental landscapes hydrated without overwatering will remain a top priority. Consider walking your landscape and note any patterns of dryness that may lead to irrigation repairs. Garden clean-up will continue in earnest; where there are turning leaves, they will become leaf piles within days. It should be noted that a few small piles support native wildlife, from small mammals to insects, so there is a benefit of leaving such piles alone over winter. For the remainder, a healthy garden or landscape means the removal of leaf debris within days of it dropping. Leaves that remain piled on lawns, ground covers, and other plants run the risk of rotting the covered plant material. Collected moisture, rotting debris, and lack of photosynthesis may lead to stressed and decaying plants. Yes, I just said to leave a few piles, but we have to be smart about their locations and what will be affected by such practices. Most landscapes offer such opportunities so that we can help local fauna in pretty simple measures. To make things more confusing, another benefit of keeping leaf debris is its use as compost or mulch, which is better than hauling in new material.