Cool Season Crops Guide for San Diego Gardens
As the temperatures cool in Southern California, our gardens require a transition as well. Warm-season plants are exhausted by autumn after months of growing. Tomatoes stop producing flowers, cucumber vines wither, and pepper plants look blighted. It’s simply the end of their season, and the kickoff of the season for plants that thrive with dimmer, shorter amounts of light and chillier temps. In the cool season, we welcome greens and bulbs.
Cool Season Crops: When, Where, and Why.
San Diego County spans two USDA Growing Zones: Zones 9 and 10. In 2023, the USDA released an updated Plant Hardiness Map, which reflects shifts in average annual minimum winter temperatures across these regions.
Zone 10a (warmer coastal areas): Coastal San Diego, from La Jolla to Imperial Beach
Zone 9 (cooler inland areas): Inland valleys and foothill regions east of El Cajon and Santee
Most of San Diego falls within Zone 10a. Understanding your growing zone is important because it helps guide ideal planting times, especially for cool-season crops which thrive in milder temperatures.
Unlike colder regions in the US, Zones 9 and 10 allow for year-round gardening with two primary seasons: warm and cool. Cool-season crops perform best during the fall, winter, and early spring months.
Your specific location within San Diego will influence exactly when to plant. Gardeners in the cooler Zone 9 can typically start cool-season crops earlier in the fall, while those in Zone 10 may take advantage of our “May Grey” and “June Gloom” to enjoy a longer growing window into spring.
To find your exact growing zone, enter your zip code on the USDA website and use it as a guide to time your planting for the best results.
Setting the Stage for Your Fall and Winter Garden:
You can plant the fall and winter season crops listed below at any time during the suggested months, but consider average temperatures and don’t plant while it’s still too warm. Here are some tips to follow while you prepare your garden:
Refresh your garden bed: pull the spent plants (and if possible, compost them!) and fertilize the bed with organic vegetable fertilizer. Avoid fertilizer with a high nitrogen count (anything with double digits) because this creates an unnatural amount of quick, weak growth.
Try not to step on the bed, and avoid massive soil turnover in order to maintain the health of the soil ecology that’s built up in the warm months.
Direct-seed beets and carrots into the soil. Plant older seedlings of brassicas (kale, broccoli, cauliflower, etc.) to ensure the strongest plants possible.
Adjust irrigation settings to accommodate for less daylight and fewer scorching days. Turn off your irrigation during a rainy day, but don’t forget to turn it back on!
Cool Season Crops to Plant Now:
San Diego’s winter crops are fun because they need less daily care, mostly are unaffected by pesky root-knot nematode, demand less fertilizer than summer crops, and often produce constantly. Enjoy the season of salad greens!
Beets: Sept – May
Broccoli: Sept – Feb
Brussel Sprouts: Sept – Nov
Cabbage: Sept – Feb
Carrots: Sept – April
Cauliflower: Sept – Feb
Chard: Sept – June
Garlic: October – Nov
Kale: Sept – April
Lettuce: Sept – April
Onion, bulbing: Oct- Dec
Onion, green: Sept – May
Peas: Sept – March
Potatoes: Feb – March
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