San Diego offers gardeners a long, productive season, a distinct advantage over much of the continental United States. The region’s mild, Mediterranean-like climate allows for year-round vegetable production. Successful gardening here relies entirely on timing—planting vegetables during the months that align with their preferred temperature ranges. This guide provides the specific planting schedules necessary to maximize harvests in the unique climate of San Diego County.
Understanding San Diego’s Unique Growing Climate
Vegetable planting in San Diego differs significantly from traditional gardening calendars because the county rarely experiences a hard freeze. Most of the area falls within USDA Hardiness Zones 10b and 11a, where average minimum winter temperatures range from 35°F to 50°F. This absence of prolonged cold eliminates the need to worry about a “last frost date,” allowing for earlier planting than in colder climates.
The climate, however, is not uniform across the county due to varied topography, creating distinct microclimates. Coastal areas benefit from the marine layer, which moderates temperatures, leading to cooler summers and warmer winters. Moving inland, especially into valleys and foothills, results in greater temperature swings—hotter, drier days and cooler nights. Inland heat dictates that gardeners must adjust planting times and strategies to manage intense sun exposure.
Cool-Weather Vegetable Planting Calendar
San Diego’s “winter” growing season, characterized by mild temperatures and shorter days, is the ideal time for many popular vegetables. Planting for the cool season should begin in late summer, typically from September through early November, to allow crops to establish before winter. This window extends through February for succession planting of quick-maturing crops.
Leafy greens and brassicas thrive in these conditions. Crops like kale, spinach, Swiss chard, and various lettuces can be planted from seed or as starts from September through January. Brassicas such as broccoli, cabbage, and cauliflower should be planted as nursery starts in September or October to ensure they mature before the spring warm-up.
Root vegetables are often best planted directly from seed into the garden soil, as they dislike having their roots disturbed. Carrots, radishes, and beets can be sown from September through February, with continuous, small sowings providing a steady harvest. Planting during the cool season prevents these vegetables from prematurely “bolting,” which is when the plant flowers due to heat stress, making the leaves or roots bitter. Peas, both shell and snap varieties, are best planted as seeds from October through January.
Warm-Weather Vegetable Planting Calendar
Heat-loving crops are timed to capitalize on the long stretches of warmth from spring through fall. The planting window for these vegetables generally opens in late February or early March, when the soil begins to warm sufficiently. Tender plants, such as beans, corn, and potatoes, can be safely planted as soon as the threat of light frost has fully passed.
The most popular warm-season vegetables, including tomatoes, peppers, and eggplant, are typically planted using nursery starts rather than seeds, starting in late March and continuing through May. Planting starts gives these crops a head start, ensuring a harvest before the intense summer heat causes production to slow down. Gardeners in the warmest inland regions should aim for earlier planting dates and select heat-tolerant varieties.
Squash and melons, which are categorized as “very tender” crops, require consistently warm soil to germinate and thrive. Zucchini, summer squash, cucumbers, and melons should be direct-sown into the garden from April through June. In inland areas where summer temperatures frequently exceed 90°F, providing afternoon shade cloth can prevent the scorching of fruit and leaves, extending the productive life of the plants. Succession planting of bush beans and summer squash every three to four weeks ensures a continuous supply rather than a single, overwhelming harvest.