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Fall Gardening: September Garden Checklist Zones 9-10

There is still plenty of warmth and growing opportunities available for September gardening Zones 9-10. There is a subtle shift with the kids going back to school and visons of the temperatures cooling down just a bit. Those in warmer climates might not be experiencing that temperature shift just yet, but there is hope that the relief is on its way.

There is still plenty to do in the garden to keep it thriving and in tip-top shape. Keep your gardens growing strong with some tips from our September Garden Checklist Zones 9-10.

Autumn decoration with pumpkins and flowers

September Gardening and Planning

As we ease into September and relish the hint of relief from the heat and humidity, it’s a great time to jot down the successes and shortcomings of this garden season and start developing goals for next year. We’ve highlighted some planning essentials that will help you grow and excel even more as a gardener.

  • Take out your garden journal and walk around the yard. Make a note of high-performing and underwhelming plant varieties. Decide what plants performed best for seed harvesting. Add your favorites to your list to buy seeds or plants for next year.
  • It’s hurricane season for those gardeners on the East coast, so have a plan to bring potted planters indoors if possible.
  • Make some notes in your garden journal about the weather and how it impacted your September gardening this year. Were there any significant storms, droughts, or heavy rains?
  • Identify which spring flower bulbs you’d like to plant this fall and buy them from garden centers when the selection is at its best.
  • In recent times, there have been some seed shortages of many of our favorite varieties. Plan to harvest your own seeds, and it’s not too early to acquire your seeds for spring if they are available.
  • Stock up on seed collection envelopes, labels, and seed storage containers.
  • Sketch and/or photograph your vegetable garden layouts and keep them in your garden journal. This way, you will know how to rotate your crops for next year.
  • Think about ways to add color and draw beneficial insects to your fall gardens. Consider planting nasturtiums, marigolds, asters, cosmos, mums, and anemones.
  • Plan out your fall pots and planters. Summer blooms are fading, but there are many opportunities to add color and visual interest to your landscape. Try pairing some fall showstoppers like heuchera, mums, asters, ornamental cabbage, and variegated ivy.
  • Make a note of any diseased or spotty plants as you remove them from your garden. Include the variety of plants and where it was planted, and discard the debris far away from your garden or compost pile.
  • Decide if you will plant a cover crop this fall and acquire the seeds for planting. Not planting a fall or winter crop? Plant a cover crop in vacant garden spaces.
  • Look around your yard for anything that needs repair or change. Would you like to start a compost area? Does a fence need repair?  Does your vegetable garden need more secure fencing? Would you like to build raised beds or build some climbing structures? Is a potting bench on your wish list? Write down any materials that you might need for these projects.
  • Check back to your gardening wish list in your garden journal for any items that may be on clearance racks at the end of the summer season. Now is a great time to pick them up at a discount.
  • Consider what new perennials and shrubs you’d like to add to your landscape. Early fall is an excellent time for planting.
  • Have perennials gotten too big for their planting spaces? September is an ideal month for dividing. Consider planning a plant swap with friends and neighbors to share your garden treasures or plan to carve out a new garden bed to plant divided perennial plants.
  • Are your seed packets in a jumbled mess after this summer of vigorous planting? Consider ordering some seed organizing supplies and write this down as a late fall or winter task.

Prep & Maintenance for Fall Gardens

September gardening is for prep and maintenance. Gardeners in zones 9-10 may feel some relief from the high heat and humidity this month. If the oppressive weather of July and August kept you from completing your garden maintenance tasks, it’s time to get a handle on the gardens.

Not sure what you should be doing in the garden this month? Here are some key tasks to get you started.

Weeding in September

Keep up with organic weed control during September gardening. They are easiest to pull when they are young or after rainfall.

Hosta flower with white-green leaves surrounded by marigold

Mulching for Fall

Mulching remains on the September garden checklist Zones 9-10 because it is so beneficial to gardens. Continue to mulch your garden beds in the fall. Here’s why:

All Natural Planting Mix

Kellogg Garden Organics

All Natural Planting Mix

Product not available in AZ, CA, HI, NV, UT. For a comparable product in these states click here.

  • It gives the yard and garden a fresh look.
  • Mulch enriches the soil over time as it breaks down.
  • Mulch stomps out those fall weeds.
  • Prevents soil erosion from heavy rains, winds, and storms.
  • Retains moisture during bouts of drier weather.
  • Insulates bulbs, perennial root systems.

Late Summer Watering

It can be much drier in September for those in Zones 9-10. Watering is vital to help new perennials and trees establish their root systems and for those already set plant root systems to stay adequately hydrated.

Conversely, annual plantings are slowing down a bit in their growth, and cooler temperatures may mean they don’t need as much water as they did during the peak of summer.

If there are any water usage restrictions in your area, be sure to abide by those regulations strictly.

Fall Fertilizing in Zones 9-10

  • Stop fertilizing trees and shrubs during September gardening. Cooler weather is approaching, and new growth established from fertilization can cause those limbs to be susceptible to damage.
  • Fertilize vegetable gardens as needed. This includes gardens that include summer vegetable plants that are still producing, fall vegetable gardens, and gardens that have finished producing. Organic fertilizers help build the soil and take time to break down to be available to plants for the next growing season.
  • If you have a cool-season lawn variety, it’s time to fertilize your lawn. If you are unsure what kind of grass that you have, bring a small clump to your local extension office and ask for some guidance.

September Garden Pruning

  • Remove some foliage from pumpkin plants to allow fruits to ripen.
  • In late September, remove female flowers from squash, melons, and pumpkins and remove immature fruits from squash, tomato, melons, pumpkins, and eggplants as they have less chance of maturing fully. Pinching them off will push the energy to fruits that are already established.
  • Allow perennial plants to die back before cutting them back. Allow some seed heads to remain on plants for birds to feed on and for seed collection.
Hand planting lettuce seedlings

Other Garden Tasks on September Garden Checklist Zones 9-10

  • It’s a terrific time to divide perennials like hostas, grandma’s daisies, bee balm, phlox, daylilies, herbs, rudbeckia, Shasta daisies, etc.
  • Plant new hardy perennial plants in the cooler days of September. This gives plenty of time for roots to get established before cooler weather sets in.
  • Tidy up your garden landscape, picking up any dried foliage, dropped fruit, or dropped leaves.
  • Start assembling your fall containers. Create an eye-catching pop of color and textural intrigue.
  • Collect seeds from high-performing plants and store them in seed collection envelopes. Don’t forget to label them.
  • Plant your spring bulbs. In Zones 9-10, you may need to perform a cold treatment in the fridge for your bulbs before planting.

Fall Vegetables to Plant From Seed Now

In this video, Brijette from San Diego Seed Company in zone 10b, shows us her new seed starts and tells us how she gets her garden prepped for fall. Follow along for some cool-season garden inspiration!

Whether your garden is big or small, make the most of your space with these tips and watch the full Fall Vegetables to Plant from Seed Now video on the Kellogg Garden Youtube Channel.

Indoor Planting In Zones 9-10

If you are planning for a winter vegetable garden, begin sowing seeds indoors for cool-season succession crops.

Outdoor Planting in September

Zone 9 Outdoor Fall Planting

Gardeners in Zone 9 can plant:

Note that those plants in the cabbage family should be planted as transplants this month.

Zone 10 Outdoor Fall Planting

Gardeners in Zone 10 can plant:

  • Beans
  • Broccoli
  • Brussel Sprouts
  • Cabbage
  • Lettuce
  • Okra

Early Fall Harvesting

Those in Zones 9-10 can continue harvesting all crops that continue to produce in the vegetable garden. Gather herbs for freezing or drying. Harvest fruits from fruit trees.

Once plants have stopped performing, you can remove them from the garden to make room for your fall and winter gardens. Discard healthy spent leaves and plants into your compost pile.


Share The Garden Love


Autumn harvest and garden pumpkin decorations.
young ripe green bell pepper plant

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