That way, you can experience the benefits of a vegetable garden throughout the year, which include:
- Increasing your gardening skills with new challenges
- Saving money and enjoying fresher, more flavorful vegetables that are free of pesticides
- Trying new or hard-to-find varieties
- Sharing your harvest with family and friends
- Enjoying getting some exercise outdoors
- Reducing your carbon footprint by avoiding produce that is shipped to your area
You may want to use only a portion of your planting area for winter vegetables so that you will have room for planting warm-season vegetables in the spring without having to tear out your winter vegetables prematurely. The areas that are not planted with vegetables will benefit from a cover crop—such as clover, field peas, vetches, or fava beans—which will improve the soil in multiple ways. See the Fall, 2018 edition of Garden Notes for more details on growing cover crops.
San Joaquin County is in the Sunset climate zone 14, described as an inland area with some ocean influence. Sunset climate zones are considered more useful to gardeners than the USDA zones because they take into account not only the winter minimum temperature (which is the basis for the USDA zones), but also summer highs, lengths of growing seasons, humidity, and rainfall patterns. Of course, microclimates within our zone and even our gardens can have a big effect on how plants grow.
What to plant
You can see from the chart below that beets, broccoli, cauliflower, cabbage, carrots, chard, garlic, lettuce, onions, potatoes, and shallots can be seeded or transplanted in the winter months in our area. Other vegetables that you may wish to plant include arugula, asparagus, bok choy, collard greens, kale, leeks, mustard, parsnips, and romanesco broccoli. Even tomatoes can be started indoors or in a greenhouse during the winter. Generally, you should start plants indoors 6-8 weeks before you plan to plant them outside.
How to plant
Additional information about when and how to plant selected vegetables can be found in a chart in the California Master Gardener Handbook. If you are interested in learning about when and how to plant broccoli in the interior valleys, for instance, you will see that the best time is December through February, followed by July, and that the plants should be spaced 12” to 18” apart in rows that are 36” apart.
Vegetables can be planted in ground level plots, and some--such as broccoli, greens, onions, and potatoes--work well in containers. Raised beds are an excellent way to grow vegetables, with several advantages:
- They generally provide higher yields in less space
- The soil is easily amended
- Drainage is improved
- They are easier to maintain
- They allow for earlier planting because the soil warms earlier in the spring
- They can easily be covered with floating row covers for frost protection
Fertilizing Your Vegetable Garden
The main nutrient that vegetables need is nitrogen, which is naturally low in most California soils. It can be added alone in the form of organic or inorganic fertilizer, but a complete fertilizer that contains phosphorus and potassium is beneficial too. One of the advantages of using an organic fertilizer—such as bonemeal, cottonseed, or fish emulsion—is that it usually contains a broader range of nutrients which are released more slowly. However, they are more expensive than inorganic fertilizers and the exact amount of nutrients they provide varies. Manure will also improve soil structure (but not soil texture—the mix of sand, silt, and clay) as well as providing fertilizer. Manure from farm animals such as cows, horses, sheep, goats, and chickens can be used, but never pig manure or pet waste, because of the risk of exposure to the parasites these may contain.
Manure that has been composted to a temperature of 140° Fahrenheit should be safe to use in that the weed seeds and pathogens such as E. coli have been killed. If manure has not been heated in a compost pile, the USDA National Organic Program suggests waiting 120 days from application to harvest for edibles that grow in or touch the soil. For other crops, the recommended wait time is 90 days from application to harvest for these edibles. Another consideration is that fresh manure does not supply nutrients in a form that is usable by plants. It takes at least a month to decompose and for the excess mineral salts to be leached away, so it should be added to the soil at least a month before planting.
Additional fertilizer—either organic or inorganic--should be applied when seedings are 3-4 inches tall, with a side dressing of dry fertilizer in a trench at least 4 inches away from the plants. This will encourage growth without burning the roots. Exceptions to this guideline include tomatoes, melons, squash, and similar warm season crops. In these plants, too much nitrogen encourages leaf growth rather than fruiting.
Winter is often thought of as a quiet time for gardeners—a time for perusing seed catalogs and planning for the spring—but in our area, there is much more that can be done. Growing a winter vegetable garden can be quite rewarding and productive, and if that is not feasible, growing cover crops to improve your soil is another way to make the best use of this season.
Additional information:
Climate zones
https://cagardenweb.ucanr.edu/Your_Climate_Zone/
https://www.sunsetwesterngardencollection.com/climate-zones/zone/northern-california
Pest management for vegetables
http://www.ipm.ucdavis.edu/PMG/GARDEN/veggies.html
Soils and fertilizer in the garden
https://ucanr.edu/sites/gardenweb/Vegetables/?uid=26&ds=462
https://extension.psu.edu/wise-use-of-manure-in-home-vegetable-gardens
https://hort.extension.wisc.edu/articles/safely-using-manure-garden/
Using raised beds for vegetables
https://cagardenweb.ucanr.edu/Vegetables/?uid=20&ds=462