Many of us think of August as a time to harvest tomatoes. I'd like to suggest that August and September are also the ideal planting time for fall, winter and spring crops.
In our mild-weather valley we can plant cool-weather vegetables as late as October. How lucky are we to be able to harvest fresh vegetables from our garden almost year round? Put in a few ‘Bibb' or ‘Butterhead' lettuce seeds now and 45 days later you will have plants that can make salads all winter long if you harvest a few outer leaves at a time.
Cool-weather vegetable gardens require much less attention than summer gardens. Because our rainy season coincides with our mild winters, soil dries out slowly. Often very little watering needs to be done.
Moist soil buffers the impact of any frost because the soil doesn't get as cold as the air. Although most vegetables will not survive prolonged severe cold, cool-season crops will survive a few days of 25ºF lows and some will even survive down to 15ºF. The University of California keeps historical frost records that suggest that Napa has only a 10 percent chance of frost at the beginning of November. But the likelihood of frost rises to 50 percent in early December. You have plenty of time to plant now and have thriving plants before winter cold sets in.
Be aware that some cold-weather crops won't grow much during the winter. Root crops such as carrots, beets, radishes and parsnips will hold at maturity in the garden until you are ready to eat them. It's almost like having an extra refrigerator. Kale, cabbage and broccoli will grow slowly but do need to have a good start before the cold sets in.
When choosing cole family crop varieties (kale, broccoli, cabbage), note if they are labeled “early” or “short season.” These varieties are less hardy than those labeled as good for overwintering. Early-harvest varieties were bred for areas with winters too severe for vegetables to survive. They need to reach maturity quickly. Hardiness has likely been bred out of those plants.
Besides being able to harvest over a longer time, you will find another advantage to planting overwintering varieties of carrots, beets, spinach and kale. When these vegetables are exposed to frost, they undergo a process sometimes called cold-sweetening. The plant stores glucose and fructose to guard against frost damage. Sugar dissolved in a plant cell makes it less susceptible to freezing in the same way that salting roads reduces ice. So a little frost often makes these crops taste sweeter.
Many gardeners prefer to plant seeds for these crops directly in the ground. However, if you start seeds inside, you can pop the seedlings into ground that you are now using for a warm-weather crop, allowing you to make optimal use of valuable garden space. Local nurseries and garden centers will also have seedlings available.
Don't forget to give your soil some extra TLC. Because you are utilizing the soil year-round, remember to dig in fertilizer and organic matter more than just once a year. Twice would be good.
When deciding where to plant cool-weather vegetables, don't overlook areas of your garden that are too shady in warm weather. The sun traverses a different path in the sky in summer and winter. So new planting areas may be available. Keep in mind that salad greens and leafy vegetables require only four hours of full sun every day.
I plan to add an extra warm glow to my holiday meals by harvesting and serving vegetables from my own garden. Now that you know how easy it is, maybe you will join me.
Do you want to become a UC Master Gardener of Napa County volunteer?
To obtain an application you must attend one of the information meetings. For meeting dates, location and times or to learn more about the program and volunteer commitment see our website.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Although each of these claims may be true, for me the answer is simpler: I grow food for my table. As I have become a more knowledgeable vegetable gardener, I have wanted to increase the variety of crops I grow and to harvest year round.
Plants are adapted to grow at specific temperatures. Some annual vegetables prefer warm weather; others perform best when it’s cool. Warm-season plants grow best in daytime temperatures of 65°F to 95°F. They thrive when night-time temperatures stay above 50°F. Most of them tolerate high temperatures but are damaged or killed by frost. Cool-season crops prefer cooler soil and air (55°F to 75°F), perform poorly when temperatures are high, and tolerate or are improved by frost.
When researching average temperatures for Napa County, I found some useful graphs on the Weather Channel’s website (www.weather.com). From May to October, our average lows range from 49°F to 55°F, while average highs for the same months are 76°F to 83°F. The months of November to April see average lows of 39°F to 45°F degrees, and highs of 57°F to 71°F. If our weather is not too extreme, we can accommodate cool-season vegetables six months a year and warm-season vegetables during the other half.
So growing vegetables year-round in Napa County is just a matter of timing: growing the right plants at the right time.
Year-round vegetable gardening uses soil intensively, so maintaining fertility is critical.
Soil is comprised of four principal components: minerals, organic matter, air and water. Minerals and organic matter make up about half of the volume of typical California soils, with minerals being by far the largest part. Soil minerals are basically decomposed rock. The size of the particles determines whether your soil is sandy (large particles), loam or clay (small particles).
Organic matter consists of decomposing plant and animal residue, living soil organisms (earthworms, fungi, bacteria) and the substances they synthesize.
The other half of the soil’s volume is the pore spaces between the solid particles. In soils with ideal moisture content, the pore spaces are about half water and half air. Typical soil by volume will be about 45 percent minerals, 25 percent water, 25 percent air and 5 percent organic matter.
Soils can be coarse and sandy or fine and clay-like. Their texture reflects the mineral content, which is difficult to alter. However, increasing the organic matter in sandy or clay soils changes the way the soil aggregates, or clumps, and improves the conditions for growing plants.
Although the living organisms in soil comprise a small percentage of its volume, mounting scientific evidence suggests that these organisms play a significant role in helping plants fight disease and pests. Many soil microorganisms live in beneficial relationships with roots. These organisms digest organic matter over time and need air and moisture to survive. Even when you don’t have a crop in the ground, you need to provide an environment that encourages this soil life. In a year-round vegetable patch, you should add compost or other organic amendments at least twice a year, or each time a new crop is planted.
Our California soils tend to be low in nitrogen, a major nutrient for growing plants. Your soil may also be lacking in other nutrients. Year-round vegetable gardening can quickly deplete soil nutrients. If your organic amendments are not relatively high in nutrients, you will need to fertilize several times a year. Although you can use synthetic fertilizers, they can harm the natural soil life. Use all fertilizers carefully, following package directions and never using more than recommended.
Plants interact with soil in different ways. Just as farmers do, home gardeners should rotate crops to prevent soil-borne diseases from getting established and to foil pests that prefer specific crops.
So here’s 12-month gardening in a nutshell: plant the right plants for the season;feed the soil with organic amendments; use fertilizers as needed; and rotate plants. Then proceed to enjoy homegrown food year round.
Workshop: Napa County Master Gardeners will conduct a workshop on “Success with Veggies All Year Long” on Saturday, January 25, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn how to keep your garden soil healthy and productive, find out which vegetables to plant in what months, and be introduced to many reliable resources. Online registration (credit card only)Mail in registration (cash or check only)
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 11:00 a.m. until 1 p.m., except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.