As a gardener, I consider soil as the foundation for all I do. Like a friendship or marriage, it must be respected and nurtured if you want it to thrive and continue to be there for you. What soil isn't is dirt.
I recently read an article in The New York Times by Dan Barber, the chef and co-owner of the two Blue Hill restaurants in New York. In the article, he wrote about how much he liked a locally grown emmer,a wheat variety also known as farro. He had been extolling the virtues of this grain, but it wasn't until he visited the farm that he realized what made the emmer so delicious.
The farmer managed the soil not by adding chemicals but by rotating crops and including cover crops in the rotation. Crop rotation improves soil health which, in turn, affects the flavor of the food grown in it.
Crop rotation is another subject Master Gardeners learn about in training, and we preach it in the public workshops we offer. I thought I knew something about this subject, but after reading Dan Barber's article, I realized I had only scratched the surface in understanding its impact on soil. The article was about farming and not gardening but the same principles apply.
The practice of crop rotation has been around for centuries, and it takes many forms. It entails planting vegetable crops of the same family in different locations each year. What you plant, and the order in which you plant,makes a difference.
The reason for rotating crops is straightforward enough. Plants related to each other tend to be prone to the same diseases and insect pests. In my pre-Master Gardener days, I thought I was practicing good crop rotation when I planted tomatoes one summer, followed by potatoes in winter and chilies the following summer. But the chili plants were yellowish-green and produced scraggly, rumpled fruit, so I knew I had a problem.
These plants are all in the Solanaceae, or nightshade, family, so my crop-rotation plan was a failure. To correct my mistake, I had to take these beds out of production for a year and solarize the soil. In a nutshell, this technique involves removing all plant matter, wetting the soil, covering it with a plastic tarp and letting it bake for six to eight weeks in summer. Afterward, I planted a cover crop of fava beans.
Cover crops (also called green manure) are an integral part of crop rotation. They build productive soil, help control pests and diseases, attract beneficial insects, prevent erosion and suppress weeds.
Cover crops include grasses such as barley, oat, wheat and cereal rye; legumes like vetches, bell beans, field peas, clovers, cowpeas; and mustards of various types. All are low maintenance and require little water. To get the maximum benefit, cut the cover crop at the base when it flowers or when the seed heads emerge on grains. You can either incorporate the vegetation into the soil or allow it to decompose on the soil surface.
If growing a cover crop is not your thing, then follow another practice that Master Gardeners recommend: add compost. And we're not talking about just a little. Spreading several inches of compost on vegetable beds before planting should dramatically improve your harvest.
The next time you harvest a tasty ‘Early Girl', ‘Black Krim' or ‘Hawaiian Pineapple' tomato, remember that the soil contributed more to flavor than the variety did. On the other hand, if the tomato is tasteless and mealy, don't blame it solely on the variety. Think about how you managed the soil during the growing season.
Workshop: Napa County Master Gardeners will conduct a workshop on “Pruning Landscape Trees and Shrubs” on Sunday, June 22, from 2 p.m. to 4 p.m., at the Yountville Community Center, 6516 Washington Street, Yountville. Proper pruning enhances the beauty of landscape trees and shrubs while improper pruning can reduce their landscape potential. Learn guidelines for proper pruning. This workshop may include a field trip to observe pruning in a local garden. To register, call the Parks & Recreation Department at 707-944-8712 or visit its web site.
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.
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 10:00 a.m. until noon, except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.
It has been three years since I first saw grafted tomatoes in a seed catalog. I ordered four. I wanted to grow them and compare them to other tomatoes in my summer garden.
Last year I ordered grafted eggplant and bell pepper seedlings. I also bought the same non-grafted varieties locally and grew them all right next to each other.
This experience gave me some results that, while not scientific, I could measure.
The first year, I grew my four grafted tomatoes in a separate bed from the others. One fared poorly but the other three were tasty enough to merit saving seed.
For a number of years, I have been saving seed from the tomatoes that I like best. The tomatoes I grew from the seed that I saved from the grafted varieties did well last summer—as well as the grafted tomatoes had the year before. Since tomatoes are self-pollinating, their seeds come true—the offspring resemble the parent plant—unless the seeds come from hybrid tomatoes. In that case, the next generation may look more like an earlier ancestor than like the hybrid.
I was amazed by the rapid growth of the grafted ‘Rosa Blanca' eggplant. It had fruit prior to the non-grafted ‘Rosa Blanca'. However, after the initial rush, it sat there while the non-grafted plant grew taller and produced fruit. I had the same experience with the bell peppers. At the end of the season, the yield was almost the same.
For grafted vegetables, professional grafters choose rootstock that is resistant to virus and other soil-borne diseases. When seedlings are large enough, they are grafted onto the root material. It's a relatively simple procedure, and I was going to do it myself but the root material was only available in quantities of 100 or more. The rootstock seed, available online, is also pricy—about 50 cents per seed.
Vegetable grafting started in Japan in the 1920s, when a square watermelon was grafted onto rootstock for a round watermelon. I don't understand the advantage of a square watermelon except that it doesn't roll around. Korea and Japan have been grafting vegetables for almost a century, and the practice has now moved to Europe and the U.S.
Last summer, Sacramento Master Gardeners did an experiment, planting two 'Pineapple' tomatoes—one grafted, one not. I have grown this variety also. They concluded that the grafted plant had more problems than the one grown on its own roots, and it cost much more. In a recent issue, Organic Gardening magazine explored the benefits of grafted versus non-grafted tomatoes and concluded that grafted tomatoes did not offer any obvious advantages for the home gardener. That is my conclusion as well.
Based on my experience and my reading online, I believe that grafted vegetables are intended more for professional greenhouse growers. In that environment, crops are planted in soil that is reused repeatedly. As a result,viruses and other soil-borne diseases build up in the soil.
The home gardener can take precautions to avoid soil-borne diseases. The first line of defense is to rotate crops. Members of the nightshade family—tomatoes, potatoes, eggplant and peppers—should be planted in different areas each year.
Solarizing the soil in summer is another way to combat soil-borne disease. Wait for the summer heat to arrive, then clean up the targeted area, removing all plant material. Water well, thencover the area with clear plastic sheeting. Secure the edges andlet the soil bake. The soil under the plasticshouldreach about 140°F, hot enough to kill many soil-borne diseases. I also found that the heat kills invasive redwood roots.
Leave the plastic in place for about two months. For more information on solarizing, consult University of California sources online, such as: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74145.html
Since this is a drought year, I am planning to solarize several of my garden beds.
Workshop: Napa County Master Gardeners will lead a workshop on “Container Gardening and Succulents” on Saturday, May 17, from 9:30 a.m. to 11:30 a.m., at the Senior Multi-Use Center, 2185 Elliott Drive, American Canyon. Grow gardens that are mobile. Discover the best containers, soil and locations for your plants to prosper. Gain confidence to work with unfamiliar types of plants.Online registration (credit card only); Mail in registration (cash or check only).
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.
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 10:00 a.m. until noon, except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.