Ann Wright: December’s dormant gardens |

Ann Wright: December’s dormant gardens

Master Gardeners of Nevada County spraying dormant fruit trees in the Demonstration Garden, Grass Valley.
Photo by Ann Wright
Peach leaf curl.
Photo courtesy UC Davis

As another holiday season rolls around, and with restrictions in place due to the seemingly everlasting pandemic, the garden may be a good place to escape for a while. Although this is typically a “dormant” time for our trees and plants, gardeners generally aren’t dormant! During this unseasonably dry spell, it will be important to watch the plants – especially new plantings. All may need some supplemental irrigation until the rain resumes. There are also many things to be done in the garden in December. Be mindful that once it does start to rain again, tread cautiously to decrease the chance of compacting the soggy, wet soil.

As the leaves on fruit trees are now gone or nearly gone, this is an opportune time to begin to treat for overwintering orchard pests which arise and thrive in the spring. Dormant and delayed dormant sprays are methods of treating fruit trees for a variety of pests. Dormant sprays are applied after leaf fall when the surfaces of the tree are more accessible. Delayed dormant sprays are applied as trees begin to emerge from dormancy, just before buds open. Dormant sprays include horticultural oils (such as supreme or superior-oils), fungicides and sometimes pesticides mixed with horticultural oil. Horticultural oil is used to help control soft-bodied insects such as aphids, mites, leaf hoppers, scales and white flies.

Diseases such as peach leaf curl, shot hole fungus, and powdery mildew can be controlled by spraying fixed copper solutions. Peach leaf curl is a common fungal disease affecting several varieties of fruit trees, specifically peach and nectarine. Peach leaf curl causes redness, distortion and puckering of leaves and young shoots. In severe cases, fruit production may be substantially reduced. Solutions of fixed copper concentrate such as Kop R Spray Concentrate (Lilly Miller brand), or Liqui-Cop (Monterey Lawn and Garden) are available to consumers for home gardening. When mixed with a 1% horticultural oil, the spray will also aid in controlling some aphids, scale and mites. There are also copper soap fungicides available.

Although the toxicity of these products is considered low, care must be taken not to swallow, inhale or expose skin and eyes to the products. Wear protective gear such as eye covering, mask, long sleeves and long pants when spraying. And, remember – when using any of these products, please read and follow the instructions on the label! Treat at the beginning of dormancy in late November or December and again just before the buds begin to open in February or early March. One way to remember when to consider dormant spraying is to do so around Thanksgiving time and around Valentine’s Day. For more information about the treatment of fruit trees, consult the UC Davis Integrated Pest Management site at .


Here are some other garden tips for December:

• Garden hygiene is one of the best ways to combat pest infestations – clean up dried fallen fruit and any diseased debris under trees or around the garden.

• There is still time to plant Asian greens and lettuce – especially if a cold frame or row cover is used to protect plants. Check soil temperature and planting guidelines to make sure conditions are appropriate at specific elevations.

• There is still time to plant spring blooming bulbs such as daffodils and tulips. Keep in mind, deer and gophers love tulips, whereas deer leave daffodils alone. Choose bulbs that are firm and full.

• Now is a good time to plant or transplant seedlings of pines, cedars, firs and spruces. Prune or “limb up” mature pines, firs and cedars from December to mid-March.

• Add fresh mulch to garden beds to insulate roots and help keep weeds from germinating during winter. Further prepare garden beds by adding compost material. If composting leaves of deciduous trees, shred large leaves before composting – by weed whacking or running a lawn mower over them. Shredded leaves will compost more readily.

• Divide actively growing native perennials and grasses. Cut chrysanthemums 6 to 8 inches above the ground after fall blooms. Where other perennials are good forage for birds, leave them alone, otherwise now is a good time to cut them to the ground.

• Have some fun with garden plants this holiday season. Wreaths can be created using cuttings from conifers or native plants such as toyon or coffee berry. Other landscape plants are rich in color this time of year and may add just the right accent to decorations around the house.

• If considering gifts for gardeners, there are a number of options. The gift of a plant may be a nice addition to someone’s yard – if they are able to plant and then take care of it. Blooming plants are plentiful, and bear root trees are available to purchase or order now. The best time to plant bare root trees, blueberries, and canes is from now through January.

Enjoy the December garden and the holiday season ahead. On behalf of the Nevada County Master Gardeners, thank you for your support and participation. Our online workshops will resume in early 2021 – watch the website ( for updated workshop information. Wishing you good health and a very Merry Christmas!

Ann Wright is a Nevada County Master Gardener.

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