January, February and March can be cold and blustery. Hopefully there will be at least one pleasant day each week so these few winter chores can be accomplished without rain gear and/or three layers of clothing.
January Ideas

TWO – Sharpen pruning tools, then dry them and rub them lightly with oil to prevent rust.
THREE – Roses will beautify gardens in the spring with proper pruning this month. Use those sharp pruners from the second chore to follow rose pruning guides for beautiful roses later in the year. Vines, fruit and shade trees or grapes will benefit from a good pruning this month as well. Be sure to clean your pruners after you are finished.
FOUR – Removing landscape plants that are not doing well will make room for new, healthier, native plants that might take less water once established. Some ideas for planting include deciduous flowering cherries and plums, dormant fruit trees, Japanese maples or a bare root rose if there is room in the landscape. Deciduous vines like Akebia and Boston Ivy can be planted this month, as well. If there's room in the landscape, pick up a few summer blooming bulbs (such as dahlias, gladiolus, lilies, and begonias) and plant them in the ground where they will add color to the landscape or in a pot that can be moved at will.
In February:

TWO – Spread some love. Give a small native California plant to a friend, a neighbor, a family member, or yourself. The plant will flourish in our climate and need far less water than other specimens once it reaches maturity. A few to consider: Goat's Beard (Aruncus dioicus), Clarkia, and Sage.
THREE – Nursery's should have edibles available to plant. Look for potatoes (great fun for children to plant now and search for once they're ready to harvest), onions, garlic, asparagus, and rhubarb. Snails and slugs love rhubarb leaves, so plan accordingly.
FOUR – Feed citrus trees with a nitrogen-rich fertilizer that contains additional nutrients such as Magnesium, Boron, Copper, and Zinc.
March Notes:
ONE – Fertilize this month! Give new plants a strong start and established plants a helping hand. Garden plants, houseplants, vegetables, and cacti will all benefit from some fertilizer this month.
TWO - Prune suckers from trees and shrubs. Also prune freeze damaged plants now unless the freeze damaged plant is a spring blooming shrub. In that case, wait until after the shrub has flowered.

FOUR – March right into a local nursery to see (and maybe purchase) annuals, vegetables, and perennials that are available now to fill in those bare spots in the landscape.
Information gathered from: