UC Master Gardeners

How to manage your garden in September

Remove diseased plant material, pinch back flowering plants, aerate your lawn — and more

UC Master GardenerAugust 27, 2013 

A good option for fall color is daylily. Also consider salvia, plumbago and chrysanthemum as alternatives.

JACK KELLY CLARK — Courtesy of University of California Statewide IPM Program

Q: My garden is doing fine, and I'm not doing much except eating giant zucchinis. Should I be doing anything else? — M.P., Nipomo

A: The September calendar marks the transition to fall this month, which means subtle changes in your garden. Day length is shorter, plants are getting ready for storing carbohydrates in their roots over winter, and most of the summer crop is ready for final harvesting.

So it’s time to wrap up summer and move on to prepare for your future garden. Because of weather and daylight changes, your plants need a bit less water than they did at their high point of need in July. However, since some days are very hot in September, do continue to monitor their water needs.

This is a good time to prepare for a healthy spring garden while your plants move into winter dormancy. Remove diseased plant material, fallen fruit, and decaying vegetables and carefully dispose them. It’s best to bag this material and remove it from your garden.

Continue to pinch back flowering plants such as begonias, geraniums, and marigolds. If needed, fertilize perennial plants, trees, and warm season lawn grasses such as St. Augustine (be sure to water deeply).

Aerate your lawn before adding fertilizer or other amendments to improve absorption. Add mulch around plants. Clip evergreen hedges for the last time this year. Divide spring blooming perennials.

For fall color, add salvia, plumbago, chrysanthemum, and daylily. For winter, plant perennial herbs such as rosemary and thyme. Place lettuce, parsley, and cilantro in areas that are protected from frost. Try alyssum and forget-me-nots for ground cover and primroses and ornamental cabbage for accents.

Fall is generally an excellent time to plant trees and shrubs. As always, only choose reputable establishments to purchase your plants and always carefully inspect nursery stock for any signs of pests or disease before purchasing. Make sure the plants fit the type of soil and environmental conditions of your garden.

Also, consider the space and water they will require as they mature.

Finally, get ready for spring color by planting or purchasing bulbs now. Plant native bulbs such as Mariposa lily or wild hyacinth, crocosmia, and sparaxis. Buy freesia, daffodil, ranucula, crocus and paperwhite narcissus bulbs and “force” cold conditions so they will bloom in spring. Most of these require six to eight weeks of refrigeration before placing them in your gardens.

Got a gardening question?

Contact the University of California Cooperative Extension Master Gardeners at 781-5939 from 1 to 5 p.m. on Monday and Thursday; at 473-7190 from 10 a.m. to noon on Wednesday in Arroyo Grande; and at 434-4105 from 9 a.m. to noon on Wednesday in Templeton. Visit the UCCE Master Gardeners website at http://ucanr.org/sites/mgslo or email mgsanluisobispo@ucdavis.edu.

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