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September Gardening Tips

Garden Maintenance

  • Compost disease-free annuals and vegetable crops that have finished producing.
  • Cultivate and add compost to the soil for fall and winter vegetables and annuals.
  • Dig, divide, and replant overgrown perennials as they finish blooming.
  • Weed and amend beds before replanting.
  • If not purchased pre-chilled, put tulip, narcissus, and hyacinth bulbs in the refrigerator for 6 weeks prior to planting.
  • Sow native bunch grass seed on bare slopes to prevent erosion.
  • Mulch cane berries.
  • Consider extending vegetable season with floating row cover, mulch, or plastic domes.  (Gallon milk containers with the bottom removed work well.)


  • Grapes, use organic mulch or P only, not N
  • Mature fruit trees
  • Cool season turfgrass with N
  • Young conifers, but not those over two years old
  • Chrysanthemums

Spray: Check the California Backyard Orchard website for current information.

  • Table grapes for powdery mildew

What to Plant in September


  • Sow seeds for columbine, lupine, California poppy.
  • Divide and replant perennials.
  • Transplant cool-weather annuals such as violas, pansies, fairy primroses, calendulas, cyclamen, stock, and snapdragons.
  • Divide and replant bulbs and rhizomes. 


  • Transplant cabbage, broccoli, cauliflower, and kale.
  • Direct seed beets, bok choy, spinach, lettuce, peas, radishes, carrots, chard, parsley, and cilantro. 


  • This is the ideal time to sow a new lawn or reseed bare spots.
  • Think about reducing the size of your lawn to conserve resources.

Cover Crops

  • Seed for erosion control on slopes.
  • Plant clover or fava beans to improve soil structure in your vegetable garden.