Your December garden chore list: Water wisely, plant liberally and beware of frosts

Rain Gutter Cleaning from Leaves in Autumn
Clean out rain gutters this month and put plant refuse and dirt into the compost pile.
(Lex20 / Getty Images/iStockphoto)

Winter’s cool temps have finally arrived, and long-term forecasts suggest some rain this month. But as we’ve seen, rain isn’t what it used to be.

In past years, we turned off irrigation systems after the first good soak in November. This year, there were no good soaks in November, so irrigation systems are still on.

That said, with the sun lower in the sky, short days and cool temperatures, gardens don’t require irrigation as often as they did in summer. Keep the minutes of irrigation constant, but don’t run the system as often.

Water works

Be prepared for dry conditions and be prepared for big rainstorms.


Preparations start from the top:

  • Hire a certified arborist to evaluate your trees. Have them check for weak branches that could drop and poorly rooted trees that could topple in a storm. They should check for borer-infested trees that need to be removed right away so borers don’t spread to still-healthy trees. If there are trees to be trimmed or removed, only work with companies who have a certified arborist on site while trees are being worked on. Make this an annual task.
  • Clean out the rain gutters. As leaves and debris accumulate in the gutters all year, by winter there’s no room for rainwater. Instead, the water flows over the edge of the roof and beats up the plants below. If the “gunk” that comes out of the gutter is primarily dirt, decaying leaves and plant parts, simply add it to your compost pile.
  • When Santa Ana winds are predicted, water deep and long the day before.
  • Install straw-filled wattles horizontally across steep slopes that are newly planted. The wattles are like speed bumps to slow water as it flows downhill.
  • Install swales and redirect downspouts to the swales. Allow water to pool while it absorbs into the surrounding soil. Think of it as banking water long-term for later withdrawal by plant roots.
  • Connect a series of rain barrels to increase your rainwater storage capacity. Better yet, install a high-capacity cistern to hold rainwater either above or below ground.
  • All water-capture systems should include a diversion valve so the first flush off the roof can go down the drain. Pollutants and debris land on the roof throughout the dry months. Most of it rinses off with the first rainfall, so let the first flush go, then collect what falls after that.
  • Don’t let water accumulate in dishes under potted plants since constant moisture can drown plant roots. Turn over dishes and buckets so they don’t become mosquito nurseries. Keep water moving in birdbaths, or change the water frequently to keep mosquitoes from breeding in them.

Walk softly

Cooler, wetter weather is a great time to work in the garden but wait a few days after a rainfall. Walking on wet soil compacts it.

Go native

Plant natives, plants from other Mediterranean climates and desert climate plants too. They’ll establish now to tolerate next summer’s heat and drought.

Take a hike

Look to the hills. The native plants are in active growth cycle now. What’s green? Chaparral, coastal sage scrub and other native habitats are alive and green this time of year. Enjoy scampering lizards and chirping birds. Let the plants along the trail teach you what to plant in your garden.


Trees and shrubs

Except where there’s a hard freeze, continue to plant oak trees, lemonade berry, toyon, Ceanothus and other California native shrubs. You can also plant Australian, South African, coastal Chilean and Mediterranean plants. Consider bay, Protea, cone bushes, Grevillea and related plants.

Think habitat

Plant ornamental vines along the coast and in inland valleys. Try native coral vine (Antigonon leptopus) or Dutchman’s pipe (Aristolochia californica), both of which create habitat for native pipevine swallowtail butterfly. ‘Roger’s Red’ is a vining ornamental grape whose leaves turn brilliant vermilion in the late fall. Your garden’s wildlife will appreciate the juice of ‘Roger’s Red’ small purple fruits, despite their large seeds and bitter skin.

Save the succulents

Take care not to overwater succulents. Too much water can rot them.

Go shopping

Succulents and Mediterranean climate plants look great in late fall and winter. This is the time to shop, plant and enjoy.

Heal nature

Plant trees to fight climate change. Commit to planting two new trees in your garden this winter, although those in fire-prone areas will need to take extra precautions.

Site deciduous trees on the south or west sides of your home for cooling summer shade. In winter, the leaves drop, so the sun can warm your home. Deciduous trees are part of nature’s powerful heating and cooling system. Trees are one way to reduce the amount of carbon dioxide produced in cooling and heating your home.

Miniature succulent plants
This is a great month to shop for and plant succulents.
(kynny / iStock / Getty Images)

Prune carefully

Prune deciduous fruit trees like peaches, plums, apples and apricots now. Different kinds of fruit trees produce fruit on different parts of their branch. Apple trees, for example, grow short side spurs where the flowers and then the fruits develop. Pluot trees fruit along the length of their branches. Figs make fruit at the tips of branches. Do your homework before you start to prune so you don’t remove the wood that will make next year’s crop.


  • Before you prune deciduous trees, strip off any remaining leaves.
  • With all trees and shrubs, make your first pruning cuts to remove dead branches, branches that point to the center of the tree, diseased branches, and those that rub against each other. Once that basic maintenance is done, prune to shape, and to optimize growth and production.
  • Work clean. Disinfecting pruning shears, saws, loppers, etc. between plants stops the spread of diseases and pathogens from one tree to the next. I use spray bathroom disinfectant to clean all of my tools. When I am done for the day, my tools get sprayed again and dried, and then the moving parts get lubricated before I put the tools away.

Spray … 3 times

Spray to kill overwintering insects, bacteria and fungi. Use liquid copper solution to prevent the dreaded peach leaf curl next spring. Spray horticultural oil to suffocate scale, whiteflies, mealy bugs and other tiny pests that overwinter in the bark. Spray once, wait a week or two, then spray again — and if you have time, do a third spray too.

Pruning roses

Don’t prune them down to the nubs. Instead, let them grow large and bushy. Since roses flower at the ends of branches, the more branches, the more flowers.

Plant veggies

Plant winter vegetable seeds now, including beets, turnips, radishes, carrots, rutabagas, parsnip and parsley. Greens and cabbage family plants (broccoli, cauliflower, etc.) can be planted from seed or as seedlings. Plant fava beans, leeks, onions and celery plants too.

Watch for frost

We don’t get hard frosts, but plants from coast to mountains can suffer frost damage on a cold night.

Move cold-sensitive container plants like plumeria, tender bromeliads, tender succulents, etc. under the eaves to protect them. Cover cold-sensitive in-ground plants with floating row cover (not plastic). Use clothespins to secure the covers in place.

Do not cut off frost-damaged leaves, stems, etc. Leave them in place to protect the rest of the plant from future frosts. Once the last frost passes in spring, it’s safe to cut off all the damaged plant parts.

Clean up the garden

Many plants accumulate dead, brown branches underneath healthy green growth. This is a good time to figure out what is still healthy and living, and what is dead. Cut out the dead so the plant resprouts healthy and green next spring.


Sterman is a garden designer and writer;