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December Tips & Events for Santa Clara County
“Don’t judge each day by the harvest you reap but by the seeds you plant.”
— Robert Louis Stevenson
Leafy Salad Plants
Harvest your leafy vegetables early and often. Many leafy vegetables will bolt (go to flower) quickly if not harvested. When you harvest lettuce or similar greens, remove only the outer, older leaves. New leaves will continue to grow from the center and you'll be able to eat salads all winter long. Harvest head lettuce all at once when the head is full and firm.

Photo: L ettuce, by Pamela Roper
Peach leaf curl symptoms (UC photo by Jack Kelly Clark)
Peach Leaf Curl
To prevent peach leaf curl, use resistant peach and nectarine varieties where possible (see the UC
Pest Note on peach leaf curl Resistant Varieties section.) For nonresistant varieties, treat trees with a fungicide such as a fixed copper spray every year in December to January. When applying any fungicide, it is essential to cover the trees to the point of runoff or until they are dripping to obtain adequate disease control.

Photo: Peach leaf curl symptoms, by Jack Kelly Clark
Free Firewood Sign by Karey Windbiel-Rojas
Don't Move Firewood
Tree-killing insects and diseases can lurk in or on firewood. These insects and diseases can’t move far on their own, but when people move firewood, these pests can jump hundreds of miles. Beetles that have done significant damage in Southern California are the Goldspotted Oak Borer and Invasive Shot Hole Borers . Let’s keep them out of Santa Clara County.

More Information: Nature Conservancy

Photo: Karey Windbiel-Rojas
California Fuchsia
Perennials and Bunch Grasses
Winter is a good time to cut back perennials and bunch grasses. You can cut back some perennials all the way to the ground. These include yarrow, hummingbird sage, goldenrod, California aster, and most kinds of California fuchsia. You can divide other perennials at this time, such as Douglas iris, alum root, seaside daisy, woodland and beach strawberry, yarrow, yerba buena, daylilies, and chrysanthemums.

You can propagate bunch grasses, sedges, and rushes by division this time of year. Examples of bunch grasses are purple needle grass (state grass of California), fescues, blue grama, leafy reed, oat and deer grass. Some sedges are the meadow, clustered field and San Diego sedge. Rushes include the common rush and the California gray rush.

Photo: California Fuchsia, by Agi Kehoe
Frost avoidance and dealing with damages
Frost Protection
Watch out for those chilly nights with temperatures below 30°F. You need to protect tender plants such as avocado, citrus, and other subtropical fruit trees. You can cover them with old sheets hung on frames or poles, or with strings of incandescent outdoor holiday lights. Turn the lights on at night. Be sure to uncover the plants during the day. Don't prune frost damage until new growth starts in spring. This helps prevent further damage and allows you to see clearly which branches won't recover.

Illustration: National Weather Service
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Library presentation by Tuan Hoang
Upcoming Events
We offer free or low-cost gardening talks, workshops, and courses all over the county, as well as hosting information tables at many community events. Please join us and bring your questions!

Wed, Jan 08, 7:00 p.m.–8:30 p.m., Winter Care of Roses , Cupertino Library, 10800 Torre Ave, Cupertino

Tue, Jan 14, 7:00 p.m.–8:30 p.m., Winter Fruit Tree Pruning , Campbell Library, 77 Harrison Ave, Campbell
Visit the UC Master Gardener Program website  for additional information including an up-to-date list of events and classes .

Have a gardening question? Contact our Help Desk (for Santa Clara County residents). Start by reviewing our plant  problem diagnosis tips .
  • Mon-Fri 9:30 a.m.–12:30 p.m., 408-282-3105
  • Fri ONLY 1:00 p.m.–4:00 p.m., 650-329-1356 (Closed Dec. & Jan.)
  • Or send us your question online

The University of California Cooperative Extension (UCCE) Santa Clara County Master Gardener Program volunteers are trained under the auspices of the UCCE. Our mission is to promote sustainable gardening practices by providing up-to-date, research-based horticultural information to home gardeners.

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