Saturday, December 7, 2013

What to Do After a Hard Freeze

Sometimes a gardener feels as if they're in a heavyweight boxing match: Your Tender Plants vs. Mr. Freeze. Your citrus, succulents and perennials that may thrive in milder climates might be able to take a frosty punch or two here in the Sacramento/San Joaquin Valleys, foothills, and inland portions of the Bay Area. But five or six chilling blows to the flowers, leaves, stems and roots? 

We aren't talking about light frosts, or temperatures that hover around 30 degrees (F) for a couple of hours; that would be normal for this time of year. What area gardeners are going through right now is a week of extended hours of below freezing overnight temperatures, with prolonged bouts of plant-killing cold in the mid-to-low 20's. 

So, what should a shivering gardener hard freeze? Should they:
a) remove all plants that look frost-bitten; 
b) prune away all freeze-damaged plant parts;

c) Purchase and plant again this month those same varieties of trees, shrubs, perennials and annuals;
d) Water the garden, even if the plants resemble toast;
e) Fight the urge to prune and plant by staying indoors, next to the wood stove.

The answers happen to be the easiest to accomplish on a cold weekend: d) and e).

If plants in your garden look blackened and wilted now, new growth may emanate from the base of the plant when the weather warms up in a couple of months.

New growth beneath the frosted branches of a geranium.

Pruning away the dead portions now exposes buds that may still be alive; another frosty morning could wipe out those survivors. 

The average frost season for Sacramento is about two months, primarily December and January. But temperatures below 32 have been recorded as early as the first week in November; as late as the third week in March.

So, keep the shears in the garage and let the dead portions of the plants protect the understory.  

It may take until mid-Spring before you see new growth. Patience is key before you pick up the pruners. In the meantime, tolerate the ugly.

Make sure your garden and potted plants remain moist, especially if it isn't raining. Water gives off heat, and this can protect plants from freezing, especially borderline citrus trees, such as lemons and limes. Damp soil retains heat better than dry soil, protecting roots and warming the air near the soil.

Succulents, such as cactus, are the exception, however. According to the Arizona-based Desert Botanical Garden, most succulents survive freezing temperatures best if the soil around them is dry. 

It's dead, Jim.
Some of those dead plants may be summer annuals, such as this impatiens, which took its sweet time to croak. Mornings hovering around 25 degrees can do that to a summer annual. Put them in the compost pile; plant more in the spring, after all danger of frost.

Frosty the Ficus

What about those plants that have frozen past the point of no return? Should you replace them with the same varieties? That frozen ficus (or avocado tree) may be Mother Nature's way of telling you: "Hey! This ain't San Diego! Pick outdoor plants that can take colder temperatures!"

Oh, and keep your frost protection gear handy...just in case.


  1. I am sorry to be off-topic, but today I planned to spray my peach trees to try to prevent peach leaf curl. I was told to spray around Thanksgiving, Christmas and Valentine's Day. I did it at Thanksgiving, but it hasn't rained here since I sprayed. Do you think I need to spray again? Because of your post on the toxic effects of the spray, I don't want to do it if I can get away with just 2 sprays per year.

    Again, sorry to ask this question, but am curious. I live in Palo Alto. Thanks!

    1. If it doesn't rain, peach leaf curl probably won't be a problem. You can get away with a single spray, but that spray should be right around bud break (Feb., usually) for maximum effectiveness.