In September it is time to plant cool-season vegetables, especially leafy greens and some root crops. Sow seeds or transplant starts of arugula, broccoli, Brussels sprouts, cabbage, collards, kale, kohlrabi, lettuce, mesclun mix, mâche and swiss chard. Also consider trying joi choi, an amazing Asian green that grows well in our climate.

Along the immediate coast, you can start seedlings of dahlias, zinnias, marigolds, lisianthus, petunias and other annual flowers. Mulch these seedbeds lightly for moisture retention and to help reduce frost damage. Keep newly planted annuals well-watered until they develop two to four true leaves.

As the days grow shorter and the sun moves lower on the horizon, garden plants stall in their growth. The cooler, shorter days decrease photosynthesis and the soil dries out. Periodic Santa Ana winds, which suck moisture from the ground and air, add to the stress.

Many flower bulbs, rhizomes and corms are available in nurseries in the fall. Some can be planted right away, but others need to be stored for a month or more. September is a great month to purchase Mediterranean varieties such as ranunculus, freesia, anemone, Dutch iris, crocus and spring-blooming tulips. You can also select daffodils, hyacinths, alliums, sparaxis, chasmanthe and babiana. Many of these bulbs will need to be stored until the autumn when they will be ready for planting. Check with your local nursery for availability.