Reduce Winter Watering
Established landscape trees and shrubs, citrus trees, and succulents need watering only once every 3-4 weeks in winter. Smaller perennials may need water every 2-3 weeks, and annuals 1-2 times a week. Continue to water deeply through the entire root zone for all plants.
Prune non-native roses, deciduous shade trees and deciduous fruit trees such as apple, peach, and apricot now. Hold off on pruning native trees until after they bloom in spring or summer. Prune exotic tropicals such as bougainvillea, hibiscus, and natal plum after all danger of frost is over.
Start Tomatoes and Peppers
Sow seeds indoors for tomatoes and peppers 6 to 8 weeks in advance of transplanting outdoors after frost -- usually mid-March in the low desert. Some gardeners transplant in mid-February, but you must provide frost protection in February. Last frost dates vary widely by elevation and microclimate. High desert gardeners may have to wait to transplant until May or June and should hold off starting seeds accordingly.
Continue Planting Cool-Season Vegetables
There's still plenty of time to sow cool-season crops such as carrots, beets, radishes, turnips, onions, lettuce, and greens of all types and to transplant globe artichokes and asparagus.
Fertilize citrus trees in January or February with one-third of the tree's total annual nitrogen requirements. Apply another third of the dose in April or May and the final third in August or September. The amount of fertilizer added depends on the tree's size and how many years it has been in the ground and is listed on the container. Water plants thoroughly before and after applying the fertilizer to prevent burn.