GROW IN ABUNDANCE: Fall Gardening In San Diego - Turning Heat Into Harvest
- k-england
- 7 hours ago
- 4 min read
By Sommer Cartier, for Let’s Talk Plants! September 2025.
Fall Gardening in San Diego -Turning Heat into Harvest
When most people think of fall gardening, they imagine crisp mornings, leaves turning golden, and a natural transition from heat-loving summer crops to cool-season vegetables. In San Diego, however, fall looks and feels a bit different. Our Mediterranean climate keeps temperatures warm well into October, and sometimes even November. This condition creates both an opportunity and a challenge. With careful planning, you can make the most of San Diego’s lingering warmth to keep your garden productive while smoothly transitioning into the cooler months ahead.
The Unique Conditions of a San Diego Fall Garden
The main condition San Diego gardeners face in the fall is lingering heat. While mornings may cool down, afternoons often remain hot, and Santa Ana winds can bring sudden spikes in temperature. This means soil can dry out quickly, tender seedlings may struggle, and plants more suited to cool weather can bolt prematurely if planted too early.
At the same time, this lingering warmth can be a real advantage. While gardeners in many parts of the country face early frosts, San Diego enjoys a long, forgiving fall season. With the right crops, it almost feels like getting a second spring before winter cools things down.
Challenges to Overcome -
• Heat stress on seedlings: New plants may wilt or bolt in lingering warmth.
• Dry soil: Warm winds and minimal rainfall mean consistent watering is critical.
• Timing: Planting too early risks heat damage, while planting too late may not give crops enough time to mature before shorter days slow growth.
Tips for Success -
• Pull weeds and spent summer crops but let a few crops go to seed. This will attract beneficial insects.Â
• Add compost.Â
• Amend your soil with an organic fertilizer.
• Use shade cloth to protect young seedlings from afternoon sun.
• Water deeply and consistently. Mulching around plants helps retain moisture and keep soil temperatures stable.
• Start seeds indoors or in a shaded area. Transplant once the seedlings are sturdy enough to handle fluctuating outdoor conditions.
• Stagger your plantings. Try seeding every 2–3 weeks to account for unpredictable heat waves and to extend your harvest.
What to Plant in Late Summer and Early Fall -
San Diego gardeners have plenty of options when it comes to fall planting. In late summer and early fall, you can still plant quick-growing warm-season crops while also getting a head start on cool-weather vegetables.
• Leafy greens: Arugula, spinach, lettuce, and Swiss chard can all be started now. They grow quickly and are less prone to bolting once nighttime temperatures cool.
• Root crops: Radishes, beets, carrots, and turnips thrive in fall conditions.
• Brassicas: Broccoli, cauliflower, Brussels sprouts, and cabbage are fall staples, though they do best when started from transplants rather than direct seeding during hot weather.
• Herbs: Cilantro, parsley, and dill all love the cooler months and should be planted as the weather begins to shift.
Summer Crops That Can Carry Into Fall -
Another strategy for a successful San Diego fall garden is extending the life of your summer crops. Some vegetables already thriving in the heat can continue to produce well into the fall, especially with the right care.
• Tomatoes: With pruning and fertilizing, tomatoes often produce a strong second flush in fall.
• Peppers: Bell, jalapeno, and chili peppers are perennials in warm climates and can keep producing until nighttime temperatures drop significantly.
• Eggplant: Like peppers, eggplants love heat and can continue rewarding you with fruit well into fall.
• Beans: Bush beans can be planted now and harvested quickly before cooler weather slows them down.
• Squash and cucumbers: If planted in late summer, they can provide one more round of harvest before cooler nights stunt their growth.
Transitioning Smoothly Into Cool Season -
The key to bridging summer’s heat with winter’s coolness is layering your plantings. Keep established summer crops going while gradually filling in with fall and winter vegetables. By October, most summer crops will slow, making room for leafy greens, root crops, and brassicas to take over.
Interplanting can also help. For example, tuck spinach or lettuce seedlings beneath taller tomato or pepper plants for shade and protection while the weather is still hot. As the summer crops wind down, your cool-season vegetables will already be well established.
Starting a fall garden in San Diego requires balancing the lingering summer heat with preparation for the cool months ahead. The extended heat is both a challenge and a gift. It forces gardeners to be mindful of timing yet rewards them with the chance to grow two seasons’ worth of crops back-to-back. By using strategies like shading, mulching, interplanting and succession planting, you can overcome the obstacles of heat and dry soil while setting yourself up for a healthy and productive garden that thrives well into winter.
With the right planning, San Diego gardeners can enjoy the best of two seasons: Summer favorites like tomatoes and peppers still producing in October, right alongside cool season greens and roots that are getting a jumpstart on winter.
Sommer Cartier
Master of Arts, International Development and Social Change
Clark University
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