winter gardening tips

What to do in your garden in September

September marks the beginning of fall and getting ready for winter. In this blog post, we’ll discuss what to do in your garden in September.


what to do in your garden in SeptemberIt’s time to start thinking about and ordering spring-flowering bulbs, such as Crocus, Hyacinth, Daffodils, Dutch Iris, Freesia, Anemone, Oxalis, Ranunculus, Watsonia, Tulips, and more. As a rule, larger caliber bulbs give big, showy displays, but generally cost more.

When you are planting your spring bulbs, remember that a mass planting of one flower type or color will produce a better effect than a mixture of colors. Bulb blooms stand out more vividly if displayed against a contrasting background. For example, white Hyacinths among English Ivy, yellow Daffodils against a ‘Burford’ Holly hedge, or red Tulips towering over a carpet of yellow Pansies.  If you are not sure which end of the bulb is the top, plant it on its side. The stem will always grow upright.

For best flowering, store them in a paper bag in the crisper section of your refrigerator (away from apples) for at least six weeks before planting.

Select some drought-resistant accent plants for your landscape that will provide autumn color. Trees that turn red include Dogwood, red Maple, black Gum, Sweet Gum, and red or scarlet Oak. Shrubs with red fall foliage include Viburnum, Winged Euonymus, and Barberry.


Two weeks before planting, amend, rototill and fertilize the beds you plan to use for cool-season vegetables, such as Beets, Cauliflower, Brussels Sprouts, Cabbage, Broccoli, Kale, Kohlrabi, Chives, Collards, Celery, Onions, Parsley, Parsnips, Peas, Radish, Spinach, Lettuce, Turnips, and Swiss Chard. In addition, you can also pot up Chives, Parsley, and other herbs, and bring them into a more sheltered area or into your house to extend the growing season.

Fall is usually a good time to plant trees and shrubs, especially in California. Research has shown that roots will continue to grow until the soil freezes. This is true for both evergreens and deciduous plants.

You can now start taking cuttings of your annual plants to bring indoors and carry through the winter. Geranium, Coleus, Fuschia, and other plants do best when stem cuttings are rooted and kept in pots indoors through the winter. Be sure to place pots where they receive plenty of light.

There are many great fall flowering perennials like Salvias, Gaillardia, Echinacea, and more. It’s nice to have perennials that flower in different seasons in your yard.  You may also plant Peonies now, but make sure the crowns are buried only 1 1/2 to 2 inches (3 to 5 cm) below ground level. Deeper planting keeps the plants from blooming. You can also plant annuals that prefer the cooler weather, such as Pansy, Viola, Snapdragon, Stock, Calendula, Iceland Poppies, and California Poppies. Bearded Iris and fall crocus should be planted in September for best growth, though bearded Iris can be planted in October and November as well.

Fall is also a great time to plant and divide perennials and shrubs for next year’s garden. By planting in the fall, your plants do not endure the stressful summer heat during establishment and have time to form sufficient root systems before the onset of winter dormancy.


  • Now is the time to maintain your lawn for winter annual or perennial weeds that germinate or form rosettes in the turf during the fall. Rejuvenate cool-season lawns by plugging, reseeding, and fertilizing.
  • Don’t retire the lawnmower when the growth of your lawn slows down this fall. As long as the grass continues to grow, it should be mowed.
  • Don’t allow leaves to accumulate on the lawn. Rake them up regularly, and store them in a pile for use as mulch in your garden next summer. If leaves accumulate on your lawn and become matted down by rain, they may kill the grass. You can help leaves break down more easily by running a lawn mover back and forth over the pile. Put the shredded leaves directly onto the garden or compost pile.
  • Dig, divide, and re-plant over-crowded perennials that have finished flowering like Agapanthus, Daylily, Penstemon, and Coreopsis to name a few.
  • If your tuberous Begonias are beginning to mildew, stop watering and let them dry off, then dig them up and allow them to dry out, and store them for the winter in a cool, dark place.
  • As the nights become cool, caladiums and other warm summer bulbs will begin to lose leaves. Dig them up, allow them to dry, and store them in a warm, dry place.
  • Prevent citrus from drying out and splitting as they mature by giving trees deep soakings during warm fall weather.
  • Pick up fallen, decomposing fruit that could harbor insects and diseases. If fruits look infested, toss them in the garbage, you don’t want to add diseases or pests to your compost pile.
  • Rake up leaves, twigs, and fruit from apple trees, and dispose of them in the trash to help control disease.
  • Autumn is a good time for improving your garden soil. Add manure, compost, and leaves to increase the organic matter content. Before adding lime to your soil, have your soil tested to determine if your soil is acidic and needs lime.


Harvest garlic when the tops die down. To prepare garlic for long-term storage, cure the bulbs for four to six weeks in a warm, dry, shady location where there is good air circulation. Pile bulbs no more than two to three deep. After curing, store in a cool, dry, well-ventilated spot.  Pick all remaining fruit.  Figs should be ripening and ready to be picked as well.

Weed and Pest Control

  • Mites, thrip, and scale are prevalent this time of year, causing a lot of damage. Black sooty mold on the leaves is usually a sign of insect infestation. Use any of the safe insecticides on the market to control these destructive creatures. Control spider mites with insecticidal soap or spray light horticultural oil on infested plants in the early morning or early evening.
  • Powdery mildew becomes more abundant following periods of cool weather. Infected plants are covered with a white, powdery growth.
  • If you find having issues with weeds in your lawn, especially crabgrass or annual bluegrass, then now is the time to apply the Master Nursery Pre-Emergent Lawn Food. This will keep seeds from sprouting and multiplying. You can do this again in February.


All in all, September is a busy month for gardeners, and we hope you enjoyed our what to do in your garden in September article.

Happy Gardening,

from the folks of Shamrock Landscape in Benicia!

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