Gardener’s Corner

December 2022

Monthly Article by Cate White, San Joaquin County Master Gardener

Winterizing Your Garden

Editor’s Note: This is a column previously published in December of 2020, but with the early start of freezing temperatures, it is particularly pertinent this year.

Now that cold weather has arrived and winter is just around the corner, it’s time to prepare your garden for cold weather. Average frost dates in our area run from mid-November to late February or early March. Brief light frosts are unlikely to be dangerous unless your plants are very sensitive, but prolonged cold or temperatures under 28 degrees are more serious. Early fall and late spring frosts can be the most damaging. Watch for clear skies and low humidity combined with low temperatures and follow weather forecasts so that you can take appropriate action.


To begin winterizing your yard, make sure it has a good layer of mulch, which helps to keep warmth in the ground.  Remember to leave an area 4 to 6 inches in diameter around each plant free of mulch to avoid rotting around the base.  When leaves fall, rake them off your lawn, and use them as additional mulch around your plants.  This prevents fungal growth in your lawn while adding nutrients to your plant beds. 

Cover frost sensitive plants before sunset to keep in ground warmth. Avoid letting covers touch plant foliage; place them over stakes surrounding your plant. Remove the covers on sunny days. Keep ground around frost sensitive plants moist, since damp soil holds warmth better than dry ground. For citrus, be aware that young trees are the most prone to severe frost damage, while mature trees may not be seriously affected. Wait until spring to be sure affected branches are dead before removing them. Another strategy for protecting sensitive plants is to drape them with a set of little Christmas lights, which produce enough warmth to prevent damage, while adding a festive twinkle on cold dark nights. Be sure to use old fashioned incandescent lights, not the newer LED types.

Ivy Topiary

Frost sensitive plants in pots should be kept moist and moved under a sheltering roof for protection.  Consider moving especially sensitive plants inside until the weather warms up.

 Since this is also the holiday gift-giving season, remember that plants can make great gifts.  Poinsettias are popular as are various types of evergreens.  Poinsettias will last inside for several months but will eventually grow leggy and stop blooming.  Our area gets too cold in the winter to grow them outside, so they are best used as temporary decoration.  Evergreens are also popular, but they should be kept in the house for short periods only since house temperatures are too high and humidity levels are too low for them to last long inside.  They can be planted in pots and kept outside most of the year and moved inside briefly for decoration.  One evergreen plant that does thrive inside is ivy.  Ivy does well in the lower light conditions inside homes and can even be trained into topiary shapes such as small trees.  Amaryllis bulbs make terrific holidays gifts, since they grow so quickly that you can almost see it happen, and they produce beautiful big flowers. 


If you are planning to give away citrus fruit from your yard, keep in mind that our county is under quarantine because the Asian Citrus Psyllid has been detected here.  This is an invasive pest that carries Citrus Greening disease, which has no remedy and is fatal.   Before taking citrus fruit anywhere, you must wash it carefully and be sure it is free of any twigs or leaves.  

So I hope you and your loved ones (including your plants) stay healthy and warm and enjoy the holidays!

December Garden Checklist

Reduce irrigation according to temperature and rain, being sure to water plants under eaves that don’t get rainfall. Remember not to water with in 48 hours of significant rainfall.

Continue controlling for ants and snails.

Clean up garden debris.

Wait until January to prune roses.

Spray fungicide on peach and nectarine trees to prevent peach leaf curl

Protect frost sensitive plants, and bring those in pots under cover.  Keep all sensitive plants moist.

Plant pre-chilled tulip and hyacinth bulbs outside now.

Purchase cyclamen, violas and primroses for winter color in pots or flowerbeds.

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