What to do in your Northern California garden in December
Bypass crowded malls and head to nurseries this month for plants that the gardeners on your list can enjoy long after the holidays. For an edible treat, tie a bow around a dwarf citrus tree or a cluster of strawberry plants. For something in bloom, choose a camellia, Christmas cactus, cymbidium, kalanchoe, or moth orchid.
For best selection, shop for bare-root roses this month.
December's not too late to plant bulbs such as tulips that have already been prechilled for 6 weeks. Unchilled tulip blooms may be smaller, and bloom on slightly shorter stems.
Camellia sasanqua and early-flowering varieties of C. japonica are blooming, making now a good time to choose them for flower color. Sasanquas tolerate more sun than japonicas, and they make good espaliers, groundcovers, informal hedges, and container plants. White 'Setsugekka' and red 'Yuletide' are upright growers. White-and-pink 'Hana Jiman' has open growth; deep pink 'Tanya' is a good groundcover. Use japonicas singly, as accents, or train them against a fence or wall as espaliers. Look for 'Alba Plena', 'Daikagura', 'Debutante', 'Elegans', and 'Wildfire'.
For winter color in containers and garden beds, stock up on cyclamen. Flowers come in a rainbow of colors ― from bright pink and coral to lavender, red, and white ― some with ruffled petals. Give cyclamen a spot that gets part shade or morning or late-afternoon sun. To plant, set crowns (base of plants) slightly higher than the surrounding soil. If possible, protect blooms from rain, which causes spotting on petals. Zones 1-2: Grow cyclamen in a cool bright location indoors.
Distinctive blooms in shades of pale lime, burgundy, pink, and white add much-needed color to the winter and early-spring garden. Plant in well-drained soil in shade or part shade. Shop locally or order online from Big Dipper Farm.
In December, most nurseries sell a wider than usual range of conifers suitable for growing in containers as living Christmas trees. Choices include Colorado blue spruce, deodar cedar, Douglas fir, pines, and redwood. Before bringing a potted tree indoors, water it thoroughly and hose off the foliage. Once indoors, set the pot on a waterproof saucer in a cool, bright location away from heat sources. Check soil moisture daily and water as needed; keep the tree indoors no longer than 10 days. Then plant outdoors or transplant into a larger container.
Winter rains can be unpredictable. If they're light, continue to irrigate plants when the soil dries out. Also frequently check containers and plants growing under eaves where rain doesn't reach to make sure they're getting enough water. If rains are adequate, turn off the irrigation system's automatic controller (or install a rain shutoff to do it for you).
For the freshest tree, look for one that is stored in water at the Christmas tree lot. After you get it home, remove an inch off the bottom of the trunk with a saw, place the trunk in a bucket of water, and store the tree outdoors in a shady area overnight. Before setting the tree in a stand, saw another inch off the bottom (you may need to remove some branches, if they start low on the trunk). Use a stand with a large reservoir, and keep the reservoir full (check it daily the first week).
Young citrus trees are more prone to frost damage than older trees. Also, immature fruits up to ½ inch in diameter are damaged at higher temperatures (around 30°) than larger, ripe grapefruit, lemons, mandarins, and oranges, which can tolerate temperatures down to 26° for short periods. If a heavy freeze is predicted, cover citrus trees with burlap draped over stakes, if possible; keep the fabric from touching the leaves or fruits.
Apply dormant spray to smother overwintering insect eggs and pests such as aphids, mites, and scale, on deciduous flowering and fruit trees as well as roses with dormant oil after leaves have fallen. For complete coverage, spray the branches, branch crotches, trunk, and ground beneath the dripline. Also, rake up and destroy any remaining fallen fruit and leaves. To control peach blight and peach leaf curl, spray with lime sulfur mixed with dormant oil after leaves have dropped. Repeat in February, just before buds show color. Spray on a dry day and follow label directions carefully.