By Season: Winter in Your Garden
What to Do in December / January / February
Inventory all sprays and pesticides; take outdated or unneeded chemicals to a hazardous waste center. Find a hazardous waste drop-off location in San Mateo County here. For disposal in San Francisco County, check here.
- Cool-season annuals such as violas, primroses and pansies.
- Shrubs and trees so that roots will get established in time to promote lush spring growth
- Inspect lawn and manage rainy season weeds before they flower.Turn compost to keep it moist, but not soaking.
- Cover compost during the rainy weather to prevent it from becoming waterlogged.
- Add mulch to garden beds where bulbs are planted, and to any bare ground to prevent compaction from rainstorms.
- Prevent compaction and poor aeration of soil by avoiding working, walking on, or using heavy equipment on wet soil.
- Watch for water that may collect after rainfall. Repair any problems in low or poorly drained areas in the landscape. Reduce irrigation or turn it off completely if rainfall is adequate.
- Be aware of frost warnings and protect sensitive plants. Light Frost 32°-29° / Medium Frost 28°-25° / Heavy Frost 24° and below for 4+ hours. If frost is forecasted, watering plants beforehand will safeguard dry roots.
- Maintain and repair garden tools:
- Clean and sharpen dull blades, lubricate garden tools and repair damaged grips.
- Clean with soapy water and a wire brush or steel wool and air dry. Apply a light coat of oil to prevent corrosion.
- Sand and rub down tools with wood handles with linseed oil.
- File cutting tools.
- Store tools in a dry, covered area.Shovel blades don’t need to be sharpened but remove any metal that folds back on itself. Have your lawn mower serviced to get a jump on spring non-chemical methods such as cultivation, hand weeding, or mowing; use toxic chemicals as a last resort.
- Destroy all roots and underground parts and do not add weeds with seeds to your compost pile.
- Indoors, keep holiday greens well watered or mist daily. Keep trees and greens away from hot sunny windows and heat sources. If you decorate outdoors with poinsettias, bring them in out of the cold at night.
- Start planning your summer garden!
- Water if winter rains are inadequate especially plants under overhangs.
- Pull those weeds before they go to seed.
- Plant dormant fruit trees and roses.
- Plant bare-root plants, including roses, shade trees, vines, fruit trees, flowering shrubs and berries.
- Top dress tender plants with light mulch.
- Keep your garden clean. Prune and cut back overgrown perennials, roses and shrubs. Remove plants that are not doing well to make space for healthier ones.
- Protect plants when nights get frosty. Cover them when necessary and keep them hydrated.
- Prune roses and fruit trees.
- Pick up dead Camellia blossoms to prevent petal blight.
- Indoors, heat dries out houseplants more quickly. Keep them watered.
- Feed the birds in your garden. Favorite food sources are black-striped sunflower seeds, red and white proso millet, peanuts and a fresh hummingbird feeder..
- Consider starting artichokes, asparagus, rhubarb.
- Purchase bare-root plants in nurseries, while there is still time. They generally stop shipping in March.
- Shop for citrus trees.
- Finish pruning roses, shrubs and trees. Clean prunning tools with disinfectant spray.
- Prune and cut back perennials and ornamental grasses.
- Prune lavender back to emerging new growth for best spike production in summer.
- Continue to clean up winter debris from beds and containers.
- If starting tomatoes from seed, now is the time to start them indoors.
- Divide perennials such as daylily and yarrow, and re-plant them in bare spots around the garden.
- Outdoors, blooms will start appearing from bulbs, annuals and perennials, as well as shrubs and flowering trees.
- Attend to indoor houseplants, and perhaps add some color inside. African violets bloom now in colors ranging from white to pink to lavender to deep purple. Ferns are another good choice indoors.
Dig Deeper for Winter Edibles
Plan: Plan your year round garden and order seeds early.
Clean-up: Control overwintering pests by removing fruit mummies and fallen leaves on the ground under fruit and nut trees, especially if codling moth has been a problem. Dispose of these materials in your green yard waste bin (composting this material could reintroduce pests/pathogens).
Plant: Bare root deciduous trees, shrubs and vines (including cane berries), fruits and nuts, grapes, and perennial vegetables. For planting, care and maintenance tips see:
Feed Plants: Fertilize citrus trees in January/February just prior to bloom.
Propagate: Cool season, winter and spring vegetables should be started indoors 6-8 weeks before planting out. (Dec-early Jan). Some can be direct sown. Warm season summer vegetables should be started indoors 8-10 weeks before setting out (late Jan- Feb). Optimum soil temperature for transplanting is 55-60°.
Check our planting calendars for what to plant and when to plant it in San Mateo County based on conditions in your garden:
And suggestions for planting a year-round garden in 200 square feet in San Mateo County.
Protect: Watch for frost warnings. If a frost is predicted, protect citrus, sub-tropical and tender plants. Pull mulch away from trees and water well, keeping the root zone moist but not soggy. If not already done in November, cover trees that are sensitive to frost.
Prune: If not done in November, now is the time to prune deciduous fruit and nut trees, such as apple, pear, and stone fruits. Prune grapes and cane berries; it’s too late once they have leafed out. Learn more here about fruit trees. And check out the California Garden Web for more information.
Note: Apricot and cherry trees are the exception; prune these in July/August only.
What To Do For Winter Landscape
Plan: Select blooming azaleas, camellias and rhododendrons while you can see their color. Order summer blooming bulbs to plant in early spring.
Clean-up: Do a general clean-up of the landscape on a dry day; avoid walking on wet soils to minimize compaction
Plant: Container ornamental trees, plants and shrubs except subtropical plants. This includes frost tolerant perennials; hardy spring blooming annuals; summer blooming bulbs; bare root deciduous trees, shrubs and vines (e.g. roses); seedlings of cedar, fir, pine and spruce. Scatter wildflower seed if this was not done in November. Plant azaleas, camellias and rhododendrons.
Propagate: Start frost-tender perennials and warm season annuals.
Protect: Keep root zones moist but not soggy.
Prune: Prune winter flowering shrubs just after bloom; woody shrubs and evergreen trees; hardy deciduous trees; dormant shade trees; summer blooming vines; hydrangeas and summer blooming perennials. Roses should be pruned by mid-February. Wait to prune spring flowering trees and shrubs until after they bloom.
Winter Pests and Diseases
- Ants, carpenter bees, earwigs, snails, slugs and yellowjackets (February)
- Borers -- Fruit and nut trees (February)
Dormant sprays may be applied to control over-wintering insects, especially on apple, pear, stone fruits (apricot, nectarine, peach, plum), nut trees and deciduous landscape trees and shrubs such as roses. Check UC Integrated Pest Management here for additional information.
- Citrus -- Snails (December)
- Pine -- Bark beetles, pitch moths, wood borers (December--January)
- Sycamore -- Scale (January--February)
For further information, refer to UC IPM notes on pests of home, garden, turf and landscape.
Diseases and Abiotic Disorders
- Phytophthora root rot (December--February)
- Leaf curl - Stone fruit (December)
- Shot hole - Stone fruit (December)
- Petal blight - Azalea, rhododendron, camellia (February)
Consider dormant spraying to kill overwintering Insect eggs, mites, soft bodied insects and some scales. Spray with horticultural oils which block the supply of oxygen and suffocate pests. Dormant sprays applied in winter do not affect fruits or impact beneficial insects.
Dormant sprays may be applied to prevent disease before new growth develops, especially on apple, pear, stone fruits (apricot, nectarine, peach, plum), nut trees and deciduous landscape trees and shrubs such as roses.
To learn more, check out this information on UC’s pests in gardens and landscape.
- Citrus - Brown rot, root rots (December)
- Grapes - Powdery mildew, Eutypa dieback, cane and leaf spot (February)
- Olive - Olive knot (December-February)
- Pine - Western gall rust (December-January)
For further information, refer to the UC IPM Disease Menu.
A portion of this Winter garden checklist was originally developed by Contra Costa County Master Gardeners. Content has been expanded and adapted to San Mateo and San Francisco Counties.