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How-To Guide

How to Start a Vegetable Garden from Seed in San Diego

San Diego can grow year-round — if you plant cool-season and warm-season crops in their windows.

Vegetable seedlings in seed trays

Timing Is the Real Fertilizer

Cool-season crops prefer roughly 55–75°F averages; warm-season crops want warmer soils and nights. A soil thermometer beats a calendar guess.

Vegetable seedlings in seed trays

Materials Required

  • Season-matched seed
  • Soil thermometer
  • Fine seed-starting mix or prepped bed
  • Labels + watering can

Step by Step

  1. Pick the season, then the crop

    Warm roughly Mar–Aug (tomato, pepper, bean, squash). Cool roughly Sept–Dec and Feb–Mar (greens, broccoli, carrots, radish) per San Diego Master Gardeners.

  2. Check soil temperature

    Tomato germinates best around 65–85°F soil; at 50°F it may take 40+ days. Lettuce prefers cooler soil.

  3. Prep a fine seedbed or sterile mix

    Work beds when crumbly, not muddy. Trays: fine soilless mix — not heavy garden soil.

  4. Sow at the right depth and moisture

    Follow packet depth. Keep evenly moist until emergence. Thin ruthlessly.

  5. Harden off transplants

    Ease indoor starts outdoors over about two weeks before full sun and wind.

San Diego Tips

  • South Coast UC timing charts beat generic national packet calendars.
  • Aim for about 8 hours of sun; leafy cool crops tolerate a bit less.

Want help getting this done right? Gardens of Gold designs and installs water-smart landscapes across San Diego County. Get a quote.