Fall Seed-Starting in San Diego

On a cool fall day in late September, we gathered for a unique San Diego tradition: fall/winter vegetable gardening. While others in the country watch their fields go fallow in winter, we’re happily planting and harvesting beets, broccoli, cabbage, carrots, cauliflower, celery, kale and lettuces among others. We have two seasons in SoCal: warm season and cool season, and unlike areas that grow cool-season veggies in spring, we grow them in fall and winter here in zones 9 and 10.

We held a seed-starting workshop at our house and invited Brijette Pena, founder of San Diego Seed Company, to teach us. For those who joined us for the fall seed-starting workshop–and for those who didn’t–here are my notes!

Watermelon Radish, Tokyo Onion, Copenhagen Cabbage, Calabrese Broccoli — we can’t wait to meet you!

At our workshop we planted four types of seeds:

Broccoli (Calabrese): Broccoli are Brassicas, which are heavy feeders. They need a side dressing of fertilizer (plant food) every 3 weeks. You can use granular organic vegetable fertilizer like Dr. Earth (scratch it in and water deeply as it’s activated by water). You can also use fish emulsion. Plants absorb fish emulsion more quickly than slow-releasing organic fertilizer; it just smells really bad. But if you can stand the smell, it’s good quick nutrition. I bought a big jug of fish and seaweed fertilizer at Joe’s Hardware in Fallbrook for $39 and saw it at Green Thumb in San Marcos for $50. You can also add horse manure and compost to beds. This changes the structure of the soil, making it more light and fluffy, which is better than our heavy clay soils because roots can grow more easily and don’t get suffocated in mud.

Cabbage (Copenhagen): Cabbages are another member of the Brassica family. Remember to leave plenty of space when transplanting these into garden beds, because they can get quite large (and heavy).

Onion (Tokyo): We had a long discussion about onions, in part because I sulkily complained that you need special magical powers to grow onions in Southern California. If your heart is set on growing bulb onions, though, good options for San Diego are Walla Walla and Red Burgundy. These are short-day onions, which are the only kind we can grow in SoCal. It’s best to plant these from late October to the first week in November. Onions aren’t ready until sometime next July, so maybe don’t make them a central feature of your garden.

For our class, Brijette recommended planting Tokyo onions. These are bunching onions and should be fairly easy to grow in our SoCal winters. When planting , we lightly sprinkled seeds on the propagation mix in our trays and then lightly covered (as though with a sifter) with a little more propagation mix.

Radish (Watermelon): I have a feeling these will be pretty easy to grow. Brijette said they grow quickly and have fewer fungal issues than some other cool season veggies. She recommended interspersing radishes around veggies that take longer to grow as you can continuously plant and sow radishes while waiting for some of the longer harvests.

For all of our seed trays–which were either one full sheet of cells or a bunch of six packs–we had a big tray that goes underneath. Brijette recommended watering from the bottom, i.e. watering the bottom tray and letting the soil soak the water upward. I really doubted that the water would travel UP the soil with no roots or anything, but I was wrong. Watering the bottom tray has helped my seeds and now seedlings stay consistently moist.

What did I miss? Please share your notes in the comments and let us know how your seedlings are doing!