Region Description: Southern California Coastal & Inland Valleys

Regional Gardening Reports :: National Gardening Association

Region Description: Southern California Coastal & Inland Valleys

Zone Map
USDA Hardiness Zones
9 to 10
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AHS Heat Zones
2 to 9
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Sunset Zones
18 to 24
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Major Cities

Anaheim CA, Long Beach CA, Los Angeles CA, Pasadena CA, Riverside CA, San Bernadino CA, San Diego CA, Santa Barbara CA, Tijuana MEX, Ventura CA

The Region

Southern California's Coastal and Inland Valleys is defined as the area just south of the Tehachapi Mountains. It starts at the Pacific Ocean north of Santa Barbara, goes east to just south of Bakersfield, then along San Gabriel Mountains to San Bernardino and into Baja Mexico. The desert portions east of San Bernardino and south to the Salton Sea and El Centro, are considered part of our Southwestern Deserts region.

The Climate

This region is famous for its year-round growing climate. The two strong influences are the moderating breezes from the ocean and drying, warm winds from inland areas. These influences along with the mountains create a myriad of microclimates with varying degrees of winter chill. In some areas, during the frost season (November through January), temperatures barely dip into the 30Fs and in some years no frosts occur. Conversely, in other areas week-long hard freezes at year's-end have killed tender plants like geraniums, fuchsias, and succulents. We average about 15 inches of rain a year, but in recent years have received 5 inches one year and 40 inches another year. Rains typically start around Thanksgiving (if we're lucky), are heaviest in February and March, and end in May. Summer's high overcast mornings moderate the heat along the coast, but inland the clouds burn off to clear to hot afternoons with temperatures around 100F. Drying winds such as the Santa Ana's can dessicate plants in some areas, while coastal fogs slow plant growth along the Pacific ocean.

The Growing Season

Long springs and falls, with relatively mild summers and winters make our "Eden" a true joy to garden year-round. The vast array of micro-climates throughout the entire area allow for a diversity of plants to be grown within a few miles of each other. In warm, thermal belt areas you'll often find tropical plants such as bananas and avocados growing. However, a few miles away near some mountainous areas, cool pockets create an environment where you can grow cold-dependent, temperate plants such as such as lilacs and tree peonies. Away from the ocean, lower temperatures in winter slow plant growth from mid-December through mid-January; while summer heat precludes outdoor transplanting during July unless carefully protected and well watered. On the coast, summer fog makes maturing warm-season crops such as tomatoes a challenge.

View this week's Regional Report for
Southern California Coastal & Inland Valleys »

Published by the National Gardening Association,


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