Fall, especially October and November, is prime planting time for native plants and most perennials.
Remove fading summer plants.
Add compost to your soil, and mulch on top. Keep the mulch a few inches away from tree trucks, as they are especially susceptible to fungal infections when they stay too damp.
Plant cool season vegetables:
Brassicas, such as broccoli, kale, cabbage, and cauliflower.
Root veggies, including beets, carrots, rutabaga, and garlic.
Leafy veggies, such as lettuce, spinach, and chard.
Peas and fava beans.
Flowers, such as California poppies, marigolds, snap dragons, stock, sweet peas, and pansies.