Plotting for Winter : Some trees and plants can’t take colder Valley temperatures, but many thrive. Consider climate to achieve vivid blooms or perfect persimmons.

Attention, Valley gardeners. The days grow short, the nights are as crisp as fresh-picked apples: It’s planting season again. Time to rethink those tired perennial beds, assess last year’s garden hits and misses and head for the nursery.

But before loading down the van with shrubs and trees that look great on the lot, it pays to take stock of local conditions.

“If you start with a list of 100 plants that do well on the Westside (of Los Angeles), you’d drop 25 of them up here,” says Nancy Harrington, a Canoga Park landscape contractor who teaches gardening classes at Learning Tree University in Chatsworth.

The main reason for the gap is the colder San Fernando Valley winter, which can wipe out tender greens--especially newly planted ones--almost overnight. “During the last several years, we’ve been lulled by unusual mildness,” Harrington warns. “We forget how bad it can be.”

David Silber, co-owner with his wife, Tina, of Papaya Tree, an exotic-fruit-tree nursery in Granada Hills, estimates that the Valley gets between 250 and 700 annual hours of chill compared to 100 to 500 on the Westside.

But Silber and others point out that the cold card can, in fact, be played to our advantage. An impressive number of plants actually thrive on winter chill, doing better here than in milder zones. Included in this group are deciduous trees that blaze with autumn foliage color; fruit trees that need cold to set fruit, and deciduous shrubs that flower more profusely after a period of winter dormancy.

In the first case, says Harrington, while Southern California is not generally recognized for a showy fall, the foliage displays get more dramatic in areas with colder temperatures--and during autumns with warm days and chilly nights. She cites Westlake and Agoura as places of “flaming fall color,” and advises people around the Valley to “consider fall, not just spring,” when they plant.

Among the trees she especially recommends are purple-leafed evergreen pears (which flower white in early spring), gold ginkgos and liquidambars, and bright scarlet and orange pistacias. Her hands-down favorite, however, is crape myrtle, which leafs out bronze-red in spring, blooms in a variety of hues from July into September and blazes yellow in the fall. “If you plant one tree in your yard,” says Harrington, “choose crape myrtle. You’ll be happy all year.”

She also recommends nandina, or heavenly bamboo, for those who want their shrubs to change with the seasons. Lusty plants with a feathery leaf and creamy spring and summer blooms, nandinas can turn deep crimson in low-lying Valley areas, while their Westside relatives put on a much less impressive show.

For the fruit gardener, says Silber, living this side of the hill can mean a wider range of planting choices.

“Though even we don’t have enough cold for cherries and some other stone fruits,” he says, “we can grow low-chill varieties of apples, peaches, apricots and even kiwis.”

Among these, he suggests Anna, Dorset and Fuji apples, Mid Pride peaches, Katy apricots and the Vincent and Abbott varieties of kiwi.

He also recommends Asian pears and, one of his personal favorites, persimmons (“They grow to perfection in the San Fernando Valley”).

Along with Harrington, Silber emphasizes that plants perform very differently depending on the mildness or severity of a particular winter. His Asian pears, for example, failed to fruit this fall because of last winter’s balmy temperatures. He points out, too, that there are widely varying conditions within the Valley, with the greatest chill occurring in low areas such as Woodland Hills and the least in the northern foothills--in places like Granada Hills.

“Before you plant, you need to know your particular climate zone,” he advises, citing the climate map in Sunset’s “Western Garden Book” as a guide.

He encourages experimentation, though, particularly with a mix of tropical and deciduous greenery to provide a hedge against extremes of weather: “If it’s very warm, tropicals do better; very cold, deciduous things thrive. Plant both, you win every year.”

Gardeners also win if they hold off on planting tender plants till spring, thereby giving them several months to establish themselves before winter arrives, says Richard (Bud) Pinder, manager of Green Thumb Nursery’s wholesale yard in Canoga Park.

As a general rule, though, says Pinder, fall is the best time to plant--after the heat and before the cold sets in.

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His list of flowering shrubs to put in now includes lilac, forsythia, spirea, deciduous magnolias and flowering quince--all selections that bloom especially well after Valley winters.

They do better, too, he adds, if they are not fertilized or watered too heavily during the fall as they are starting into their dormancy.

Finally, Pinder puts in a good word for roses, which are less prone to mildew and flower more in the Valley sun than they do on the foggy Westside.

For a surprise midwinter treat, he also suggests planting sweet peas now: “They grow well in the cold,” he notes, “and they usually don’t freeze. You could have a crop by Christmas.”

Where to Go

What: Papaya Tree Nursery.

Location: 12422 El Oro Way, Granada Hills.

Hours: 8 a.m. to 5 p.m. daily, by appointment.

Call: (818) 363-3680.

Hardy Winter Basics These tough basics for the San Fernando Valley garden are recommended by Nancy Harrington, a Canoga Park landscape contractor:

INDIA HAWTHORN: Common but reliable, this evergreen shrub is drought-tolerant and long blooming.

SWEET OLIVE: Evergreen, drought-tolerant shrub withstands frost and has a sweet, heady fragrance.

HOP BUSH: Fast-growing, delicate-leafed evergreen shrub turns red in the heat and cold.

YESTERDAY-TODAY-AND-TOMORROW: This dense, green shrub goes dormant briefly and blooms in spring and summer with flowers that change color--from purple to lavender to white--over time.

JAPANESE BARBERRY: Large, dense, deciduous shrub goes red before its leaves drop and produces crimson berries in fall and winter.

BREATH OF HEAVEN: South African shrub is lacy, evergreen and flowers white or pink, even in the cold.

CEANOTHUS: Shrub, tree or ground cover, mostly native to California, is tough, glossy leafed, very drought tolerant and blooms in spring.

POTATO VINE: A hardy climber, the vine flowers profusely and stays evergreen during mild winters.