We have, on average, 275 days a year of sun. That abundance of sun provides us with two full and distinct growing seasons. Our cool growing season starts in late September as daytime temperatures drop and remain consistently below 90 degrees and it extends until April when daytime temperatures regularly rise above 70 degrees.
There's just one glitch in our cool season — our brief winter, which lasts from mid-November until late January.
Our winter lasts just nine or 10 weeks, but temperatures are cold enough so that all growth stops. In order to have a full three-to-four month growing season for cool-season flowers and vegetables, we need to set out transplants and start seeds for spring harvest now, in fall. If we wait to plant cool-season flowers and vegetables until late January, we risk damage from an early hot spell that shortens the necessary growing season.
Peas, sweet peas and fava beans should be sown in mid-October, after any threat of a late hot spell has passed. New shoots for these plants will be about six inches high by the time the first frost arrives in mid-November. The shoots will stop growing in cold weather, but really take off in late January as temperatures warm. This early planting extends the flowering season of sweet peas and ensures an early crop of peas and fava beans.
Some cruciform vegetables including broccoli, cauliflower and Brussels sprouts do quite well in colder weather. Frost actually sweetens the taste, and they continue to grow, albeit very slowly. If this next winter is mild, with no hard freezes (temperatures below 29 degrees), you might be harvesting broccoli for Christmas dinner.
Seeds for leafy green vegetables can be sown now and harvested throughout winter. Leaf lettuces (rather than the head varieties like iceberg), arugula, Asian greens, spinach, chards and kale can be harvested leaf by leaf and the original plant will continue to produce for months. Consider planting a salad bowl or two of leafy greens for salads and sandwiches on the patio. Leafy greens planted in containers stay much cleaner than those planted in the garden.
Slow-release fertilizers are ideal for cool-season crops since the capsules break down slowly over a six-month period, just long enough to provide consistent nutrients during the cooler months. Growth and root development will slow or stop during the coldest weeks. If applying liquid or granular fertilizers, stop feeding cool-season vegetables and flowering annuals in mid-November and resume feeding in mid-January.
Row covers can protect vulnerable plants (especially the cruciform vegetables) from pest insects. Frost cloth (available at most garden centers) will protect tender, new leaves from freeze damage.