San Diego Gardener
Southern California Garden Guide
Month of December
December marks the beginning of winter here in Southern California. The days grow cooler and shorter, shadows longer, and plant growth comes to a near halt until sometime in February. Normally December fulfills its winter role with cold and rain, although it can sometimes bring a heat wave that makes you swear that August has returned. So be prepared to protect tender plants from possible frost or, if the weather brings hot drying winds, be prepared to hand-water your plants.
If you're too busy to give the garden much attention this month, you're in luck, most plants will do quite well with little help from you. So if you prepared for winter in the fall, sit back and relax and enjoy the holidays. If you still haven't finished your fall gardening tasks, don't worry, the fall planting window hasn't quite closed just yet. You can treat December as part of fall and plant just about anything although most plants would have been happier planted earlier when the weather was warmer.
If you can find the time, working in the garden this month is wonderful. The weather is cool and when soil dries a little following a rain, it's perfect for digging. However be careful not to go to work too quickly after a rain because working a wet soil can physically harm it. Grab a fistful and squeeze it lightly: If it crumbles when you loosen your grip, it's just right; if it stays in a tight ball, it's still too wet.
After the holidays, if you find yourself with time on your hands or you're just an eager beaver, you can get a jumpstart on the New Year by tackling some of January's tasks. You can shop for bare root stock (roses, fruit trees, grapes, berries, strawberries, and some vegetables) in the nurseries and plant them early. It's also a good time to plant the winter-blooming camellias. Camellias and azaleas are best planted while in bloom which is helpful because you can see what colors you are adding to your garden. You can keep quite busy planting between any rains we might get this month.
Azaleas and Camellias. Plant azaleas and camellias this month. Camellias and azaleas are best planted while in bloom which is helpful because you can see what colors you are adding to your garden. Sasanqua Camellia are in bloom right now. Although the camellia sasanqua flowers are smaller and not as long-lasting as the camellia japonica, the plant blooms profusely and can take more sun.
Cool-Season Vegetables. Between harvests you can still plant most cool-season vegetables such as broccoli, Brussels sprouts, cabbage, cauliflower, celery, kale, kohlrabi, mustard, lettuce and other greens, and root crops like beets, carrots, radishes, and turnips.
Cool-Season Flowers. If you live in a mild coastal zone, there is no need to wait for spring; you can still fill in those bare spots with flowers.
Spring-Flowering Bulbs. Finish planting any spring-flowering bulb that doesn't require pre-chilling. The rule of thumb is to plant the bulbs before December 25. When planted later, the flowers will be fewer and smaller. Tulips, crocus and hyacinths should be refrigerated for 6 to 8 weeks before planting. They need cold earth so start planting between Christmas and New Year's Day unless there's a heat wave; If this occurs, wait until January but plant before January 10th.
Wildflowers. Sow wildflowers. A generous definition of "wildflower" would be any annual or perennial that reseeds itself. Under this definition fall cosmos, gaillardia, annual gypsophila, foxglove, larkspur, nasturtiums, violas and viper's bugloss (Echium vulgare). Their display can last into early summer. You also can choose from types that grow wild in California: Chinese houses, several Clarkias, chocolate-bell fritillarias, desert bluebells (Phacelia), California poppies, mariposa lilies, owl's clover, Indian paintbrush and others.
Cymbidiums. Some cymbidiums start to bloom in December although most bloom between Febuary and March. Continue to feed the plants for bloom (low nitrogen fertilizer) until the buds open.
Dahlias. Lift and store dahlias for winter. When dahlias have gone totally dormant, dig up the tubers. First cut back the tops to six inches, dig around each plant, then carefully lift each clump with a garden fork. Cut the tops back to two inches and layout the whole clump on newspapers to dry. Continue to dry these clumps in a dry shady place for two to three days then dust the clumps with sulfur and pack in perlite. Divide the clumps in the spring when growth begins. Make sure each section has an "eye" (growth bud).
Grapes. Prune Grapes from December through early January. See the Sunset Pruning Handbook for the three major methods of pruning grapes. Save the trimmings to make ornamental wreaths and baskets.
Raspberries. Cut back raspberries. Low-chill raspberries bear fruit over a long period on new wood. Rejuvenate plants this month (or in January) by cutting back to the ground all canes that have fruited.
Native Plants. This is the growing season for California Natives so if the weather is dry, water these plants. Native plants can also be pruned now. Some people do not prune natives at all but some the shape of some plants can be improved by judicious pruning.
Peaches. If your peach or nectarine had leaf curl (puckered, yellow and red leaves) this year, spray it with lime sulfur at full leaf fall. If you sprayed your peach trees in November, wait till January for the second treatment. Do not use this spray on apricot trees.
Fruit Trees. Dormant spray deciduous fruit trees. Dormant sprays such as horticultural oils or lime-sulfur are applied after a deciduous plant has gone dormant and dropped its leaves. Dormant sprays are used to control overwintering mites and insects such as scale. Lime-sulfur spray is used to control certain fungal diseases such as peach leave curl. You can also prune deciduous fruit trees this month or wait until January.
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Last update: Thu, Feb 25, 1999.