by Pat Hitchcock, UC Master Gardener of Napa County
I trained to become a Napa County Master Gardener in 2004. That same year, a few members of our group decided we could learn something by growing the same vegetable varieties in our diverse home gardens and then comparing notes. How easy or challenging were the vegetables to grow? Were they pest- and disease-resistant? How was the yield?
Over the years we have tested nearly 50 different vegetables. Last year we decided to investigate cabbage.
Cabbage is part of the Brassicaceae family, which includes broccoli, cauliflower and kale, among others. These plants grow best in cool weather. Our Napa Valley climate has two cool seasons, one in late fall and the other in spring, and we agreed to try growing cabbage in both seasons.
For fall planting we started seeds in August or early September, calculating that six-week-old seedlings could be set out in September or October and hopefully mature in early winter. Spring planting of seeds began in January so seedlings could be transplanted in February or March and mature in late spring or early summer.
We selected three different round types: a red cabbage called Ruby Ball Improved, a green variety called Katarina, and a crinkly-leaved Savoy type named Alcosa. Seeds were ordered and distributed to volunteers willing to grow them and keep detailed notes.
One challenge in fall planting is starting seeds in the middle of summer and keeping the young seedlings healthy in hot weather. Once planted, seedlings would need shade and extra water if a heat wave threatened. A second challenge was finding space in the vegetable garden for new plants while summer crops were still producing.
For seeds started in January, the challenge is providing the seedlings with enough light. And nature can throw curveballs. Last April, after field trial participants had transplanted their seedlings, we had a heat wave. Shade covers and attention to watering were necessary strategies again.
Cabbage seeds generally germinate in less than a week. However, many gardeners noted that the Red Ball variety was slower to sprout and had a lower germination rate than the green varieties.
All seedlings were transplanted when they were six to eight weeks old. By that time, they were about the same size as nursery starts. For fall, the seedlings went into the ground in September or early October so they could get established while the days were still long. Spring seedlings were transplanted in February or early March.
Trial participants noticed several pests. One gardener lost seedlings to rodents even before they went into the ground. Another gardener also battled rodents. Barriers such as cages or row cover can help foil these critters.
Aphids showed up as well and were managed with regular sprays of water. We also contended with slugs. Most of us used an iron phosphate-based bait that is safe for pets and children and accepted for organic gardens. Most aphid and slug damage was confined to the outer leaves so gardeners still harvested edible heads.
Fall-planted seedlings produced mature heads from December to March. Spring harvest was from late May into July. The fall-planted crop seemed to have a wider harvest range than the spring crop, possibly because the low levels of daylight in winter slowed the growth. No one reported frost damage; cabbage is hardy.
Participants generally preferred the green Katarina and the Savoy over the Red Ball. Some of us had never grown a Savoy type before and really liked Alcosa. Most participants said they would grow cabbage again.
The field test group was small, just half a dozen gardeners, so our results aren't conclusive. A couple of us failed to get any transplantable seedlings in the fall and had to fill in with extra plants from those who had better luck. We could have purchased plants from a nursery and saved ourselves some trouble, but we might not have been able to find the varieties we wanted to try.
Over 20 years of field testing, I have learned that even when I am indifferent to a particular vegetable, once I've grown it, I usually like it. I was one of the Master Gardeners who had never grown a Savoy cabbage before. I liked it so much that I tracked down the seed source and ordered some to grow this year. Now I just need to find more room in the planting beds.
Library Talk: Join UC Master Gardeners of Napa County for a talk on “Planning a Cut Flower Garden,” on Thursday, February 6, from 7 pm to 8 pm, via Zoom. This summer, your garden can include beautiful, colorful flowers to cut and bring into your home. Join the UC Master Gardeners of Napa County to learn about the best annuals, bi-annuals and perennials for cutting, along with soil preparation tips, starting seeds indoors, and direct seeding techniques.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description of the problem.
