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Foiling the Frost, Spoiler of Paradise

January 12, 1991|PATRICK MOTT

It's hell being a Southern California gardener. You get no slack.

Gardeners in Perth Amboy and Saginaw and Denver and Prince Edward Island can blame altitude and blue northers and permafrost and angry acts of God for their pathetic botanical showings.

But God does not get angry in Southern California. He applies another coat of sunscreen and kicks back. We are God's back-yard patio, the place He goes when He tires of freezing rain and another boring white Christmas.

The people chattering their teeth down to brittle nubs in Butte, Mont., know this, so their sympathy for a whiny SoCal gardener is necessarily limited. To the tundra dwellers, this is a place where, with a sprinkling of the right plant food, we should be able to cultivate a crop of Lamborghinis, never mind prize-winning tomatoes. We're supposed to be able to make the fabled Fertile Crescent look like just another slag heap. Trees bearing oranges the size of beach balls are supposed to spring out of the sidewalk without warning.

So how do we tell them about the frost? How do we break it to people who have to chisel their cars loose from the driveway every morning that, once every few years, we have to mother our plants deftly through a hard freeze?

Worse, how do we deal with it? Most Southern Californians know as much about frost as they do about Rubik's Cube. Frost is what forms on your margarita glass. It's what you get rid of in your refrigerator every year or so. To us it's quaint, like Amish carriages.

So when a month such as last month strikes, we go a little crazy, as if the very fabric of the universe were coming unraveled. Frost? Here? We look at our plants and, knowing nothing better to do, stand dumbly and wring our hands.

But, because frost in these parts usually is not something that arrives without warning, we can arm ourselves with a bit of knowledge. In other words, know thy garden.

Every garden has a series of microclimates, spots in the yard that are warmer or colder than others. The most dangerous areas for plants that are not so hardy--as well as vegetables--are stretches of open ground exposed to air on all sides, particularly from the north. There are also such dicey places as hollows or spots at the bottom of hillsides that trap cold air as it sinks and hold it motionless.

The best place for delicate plants is underneath something, such as the overhang of a roof or the branches of an evergreen. These overhangs trap heat and reflect it back to the plant below. Even better: Locate delicate plants under the eaves near a south-facing wall. South-facing walls absorb heat during the day and radiate it at night.

Another strategy involves putting frost-susceptible plants in containers that can be moved to the warmer parts of the garden, or even indoors, during a freeze.

If the plants are static, however, they have an unlikely ally in the frost battle: water.

According to the Orange County agricultural commissioner's office, one of the best ways to prepare for a frost is to keep the ground around plants and trees moist and "in a firm, smooth, non-cloddy condition."

Strange as it might seem, water in the area of a plant actually raises the temperature around it. In fact, sprinkling the area around, say, an orange tree, can raise the air temperature 2 to 3 degrees.

However, you need to turn the water on before the temperature drops to 32 degrees, and the water must stay on until the temperature rises above freezing.

A caution: Wet the ground, not the plant itself. Water that gets on branches and limbs can freeze up and cause foliage to break.

It pays to start thinking about watering early, in some cases very early. You should do most of your heavy watering and fertilizing in late spring and early summer, when plants are growing fastest.

Taper off the nitrogen feeding in the late summer, however, and reduce the amount of water you use. This will slow the growth of plants and keep new growth from appearing when the weather is coldest. An actively growing plant is more susceptible to frost damage than one that is dormant or semi-dormant.

For this reason, you should be particularly watchful for frosts early in the fall or in the spring after plant growth is naturally under way.

How can you tell whether frost is on the way? Obviously, the air gets unusually cold, but there are other subtle indicators: still air, an absence of cloud cover, low humidity and a temperature that drops to 45 degrees or less at 10 p.m.

If all these seem to add up, spring into action. Apart from the watering and sheltering strategies, you can care for particularly delicate plants by covering them in burlap or plastic. Drape them over a frame made of stakes so that the covering will not touch the plant (at places where the cover touches, freezing is likely). Take off the covers during the daytime.

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