Gardeners can grow most annuals, biennials, and many non-woody perennials from seed. Growing your own vegetable transplants from seed has many advantages. When compared to commonly available transplants, seeds can provide more varieties that are disease resistant and grow well in your climate. More varieties allow for a greater selection of varying mature days to help plan for an extended harvest period. Also seed packets can be saved for years if stored properly. All these factors can save money and result in a productive garden. |  Photo Credit: UC ANR |
Basics
- Start indoors for seed and plant as transplants- Broccoli, cauliflower, cabbage, tomatoes, peppers, some herbs, and flowers.
- Start from seed in ground- beans, chard, beets, carrots, peas, turnips, cucumbers squash.
- Either start indoors or directly in the ground- Cucumbers, squash, Chinese cabbage, lettuce, leeks, onions.
- Start seeds indoors or outside in a hot box (cold frame). When to start seeds varies but guidelines are on seed packages. On average, start seeds about 6-8 weeks before you want to transplant in the garden. Consider last frost date, April 7th in North County, February 15th in San Luis Obispo and South County.
- Cool weather vegetables like cabbage, broccoli, lettuce, cauliflower, beets, carrots grow best with average temperatures 55-75 degrees F.
- Warm weather vegetables like tomatoes, peppers, squash, beans grow best when average air temperatures are 65-95 degrees F. They also require soil temperature of 65 degrees F for best growth. Yellow or purple leaves are a sign of cold soil on these plants placed in the ground too soon.
 Photo credit: Kim Wilson UC Master Gardener | Seed Starting Supplies and Procedure • Seed package- light, temperature and water requirements are on the seed package. • Soilless sterile germinating mix- fine textured, well aerated commercial germination mix- not garden soil. • Containers- any container with holes for drainage- egg cartons, milk cartons, peat pots, cow pots, paper pots, purchased flats. May need to start or move up to larger containers as they grow depending on the vegetable (if potting up use a good quality potting soil). • Sterilize plastic containers with 10% bleach solution (1 part bleach to 9 parts water)- rinse well. |
Planting Seeds
- Wet germinating mix to moist, but not wet. Fill containers ¾ full and lightly tamp.
- Plant seeds at depth stated on seed package or about 2-4 times seed diameter. Cover lightly with soil. Do not fertilize.
- To promote germination- Cover containers with plastic domes, plastic wrap or bag to retain humidity. Keep in warm room (65-70 degrees) but only until seeds germinate. Use bottom heat especially for warm weather vegetables. They don’t need light to germinate, some flowers are the exception. Keep moist – do not let dry out.
- Once seedlings sprout, remove covers and put in bright area such as under grow lights (6 inches above) or south facing window. Now grow in cooler temperatures and water regularly. Apply half strength fertilizer once true leaves appear.
- Once weather and plants are ready for planting outside, harden off transplants by bringing them outside for gradually longer periods of time over a few days. Watch for wilting and place in shade protected from wind at first and gradually introduce to sun (avoid strong afternoon sun).
References
Seed starting:
Womack, Melissa. Get a Head Start on Your Garden. UC Master Gardener Program Statewide Blog. UC ANR. 2023. Get a Head Start on Your Garden by Starting Your Vegetable Seeds Indoors - UC Master Gardener Program Statewide Blog - ANR Blogs (ucanr.edu)
Von Rosenberg, Susanne. Seed Starting is Easy! Napa Master Gardener Column. UC ANR. 2019. Seed Starting Is Easy! - Napa Master Gardener Column - ANR Blogs (ucanr.edu)
Vegetable Garden Basics:
Caring for Your Vegetable Garden. UC Master Gardener Program. UC ANR. Caring for Your Vegetable Crop - UC Master Gardener Program (ucanr.edu)
Geisel, Pamela, Carolyn Unruh. Vegetable Garden Basics. UC ANR. Publication 8059. 8059.ps (ucanr.edu)
Home Vegetable Gardening. UCCE Master Gardeners of San Joaquin County. Home Vegetable Gardening - UCCE Master Gardeners of San Joaquin County (ucanr.edu)
Varland, Johannah. Vegetables: Cool Season Planting for San Luis Obispo County. Master Gardeners of San Luis Obispo County. 5609INFO_DOCS64335.pdf (ucanr.edu)
Vegetables. The California Garden Web. UC. Vegetables - The California Garden Web (ucanr.edu)
Vegetable Gardening Basics. UC Master Gardeners of Santa Clara County. Vegetable Gardening Basics - UC Master Gardeners of Santa Clara County (ucanr.edu)