By David Layland, U. C. Master Gardener of Napa County
It's that time of year: time to start thinking about planting this year's vegetable garden. It's still too early to actually plant seeds or starts but it's not too early to do a little planning.
By now the remnants of last year's garden should be decaying in your compost pile. If not, removing any plant debris from last year should be your starting point. You want a clean slate in case any of last year's plants were diseased.
Once you have cleaned up your garden beds, it's time to add compost. Ideally, you did so last fall, but if you're like me, it didn't happen. Add a good three to four inches of compost so that plants have an ample supply of organic matter to feast on all season. Such a healthy addition of compost will reduce or even eliminate the need for fertilizer.
The time-honored method is to dig in the compost, but many people are now advocating a no-till approach. Digging breaks and disrupts the long, delicate filaments of mycorrhizal fungi that live on plant roots. If undisturbed, these fungi grow downward, branching out like a second set of roots and giving plants access to nutrients deep in the earth.
If the soil is tilled, this network of fungi will need to re-establish itself. When seeds or starts are planted without tilling, they can often hook up with last year's mycorrhizae almost immediately, which gives them an early advantage.
However, soils with poor structure do need to have organic matter thoroughly incorporated into them. If your soil has too much sand or clay, if it is compacted, or if it lacks organic matter, then by all means dig.
Before deciding what to plant and where, take a trip back in time. If you are like me, you have maintained a garden journal to record what you grew in your vegetable garden each year. This information is critical as you don't want to plant vegetables in the same family in the same place every year.
Crop rotation is one of agriculture's oldest cultural practices. In a home vegetable garden, crop rotation involves changing the location of vegetable families each season. Crop rotation reduces damage from insect pests, limits the spread of vegetable diseases and improves soil fertility.
The vegetable families I use in rotation are Solanaceae (potatoes, tomatoes, eggplant, peppers); Cucurbits (cucumber, squash, melons); root crops (carrots and beets); Brassicas (broccoli and cabbage); legumes (beans and peas); and leafy greens (spinach, lettuce, kale). Ideally the same vegetable family should not be planted in the same place for at least three years. I find this difficult as most of my summer garden is devoted to vegetables in the Solanaceae family, so I'm often rotating crops every two years.
Warm weather in March tempts us to start transplanting tomatoes, peppers, squash and other summer vegetables. But it's not the daytime temperature that matters most; it's the soil temperature. Tomatoes want soil warmer than 60°F before they really start growing. Our Napa Valley soils don't usually reach that temperature until mid-April or May.
Peppers and eggplant want even warmer soil. I have planted tomatoes in early April and again in mid-May and found that the plants start ripening at the same time. So you are not really getting a head start on the harvest by planting early.
Most garden centers sell soil thermometers that will give you an accurate reading. However, if you don't want to spend the money on a soil thermometer, try the “sit down test.” Sit in thin shorts on the bare ground. If you can stay seated comfortably for 60 seconds, then go ahead and plant. Otherwise, your tomatoes will just sit there, too, and not grow. I don't believe the University of California has done any research on this method, and since I have a soil thermometer, I haven't actually tried this myself.
You have a few more weeks before planting, so sit back, relax and think about all those fresh vegetables you will be enjoying this summer.
Tomato Plant Sale: U. C. Master Gardeners of Napa County will hold their sixth annual Tomato Plant Sale on Saturday, April 14, from 9 a.m. until sold out, at 1710 Soscol Avenue, Napa. Find more than 4,000 tomato starts in 28 varieties, from popular heirlooms to new hybrids. These Master Gardener-grown seedlings include varieties suitable for eating and cooking, plus cherry tomatoes of many colors, and early, mid- and late-season varieties. A team of tomato experts will be on hand to answer questions.
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.
I've often felt overwhelmed by what seems like such a complicated task. But I've learned that pruning is really not difficult. My first tip is to be aware of how pruning affects your fruit trees.
Pruning strengthens branch structure, controls size for better fruit and easier harvesting and makes the tree more visually appealing.
If you wait until warmer weather to prune, the tree will no longer be dormant. You will waste a lot of the tree's energy if you cut off blossoms that it has already created. Pruning now increases fruit size and quality. But one of the big benefits of pruning in winter and early spring is that it's easy to see the branch structure without all those leaves.
A fruit tree's vertical branches tend to be vegetative, while horizontal branches tend to be fruiting. In other words, upright branches create the leaves that supply the energy the tree needs to grow fruit. It takes both types of branches to create good fruit.
Shade inhibits flower production on fruiting branches. If overly shaded, the tree will only set fruit on the outside edges of the branches. Good pruning produces a canopy that allows for air and light flow and makes it easier to thin and harvest fruit.
You will need clean pruning shears, loppers with a 24- to 30-inch handle, and an 8- to 15-inch curved-blade pruning saw. Do not use any kind of sealer when cutting branches. Let the tree use its own natural defenses to heal the cut.
Step 1: Clean up the tree. Remove any suckers growing straight up from the roots and rootstock. Remove any dead or diseased branches and any crossing branches that are rubbing each other. If you remove diseased branches, disinfect your shears between cuts with a 10 percent bleach solution to keep from spreading the disease to other branches. Don't leave stubs. Make cuts close to the branch or trunk.
Step 2: Thin branches to allow light and air into the canopy. A good rule of thumb is to leavesix to twelve inches of air space around branches. Smaller branches need less air space than larger ones. Branches that bend downward eventually lose vigor and produce fewer and smaller fruit. Cut off the part that is hanging down. Now look for any straight, thin, vigorous branches growing straight up from the trunk or other branches. These water sprouts mainly produce leaves. They block light and air so remove them.
Strong branches that can bear the weight of fruit grow at angles of 45 to 60 degrees. If necessary, you can often bend younger, flexible branchesto force a proper angle using sticks, clothespins or ties. If a branch has hardened into a bad position, it's probably best to remove it.
Step 3: Head back and shape.This last step is easy because you're just giving the tree a haircut. Removingsome of last year's branch growth makes a stronger support for fruit. Sun-exposed wood produces the most and the largest fruit. Do most of your heading at the top of the tree to allow light to reach lower branches. Most people prefer keeping a fruit tree under eight feed to make it possible to harvest without a ladder.
Annual branch growth can be anywhere from two inches to four feet depending upon the tree's vigor, but you should be able to identify new growth by the wrinkly ring of bark encircling each stem.
Make heading cuts within ¼-inch of a bud. New growth occurs where you make the cut, so cut just above buds that face in the direction you want the branch to grow. That bud is in charge and says, “We're going this way” to the branch.
On peach and nectarine trees, remove half of last year's growth. On fig, apple, pear, plum and apricots, remove about 20 percent of last year's growth. Cherry trees are an exception; they are only pruned in summer.
Now sit back and prepare to enjoy the fruits of your labor. If you have questions about pruning or gardening, don't hesitate to call or visit the UC Master Gardeners of Napa County. See office hours and phone numbers below.
Workshop: UC Master Gardeners of Napa County will host a workshop on “Garden Planning” on Sunday, January 24, from 1 p.m. to 3 p.m. at the Yountville Community Center, 6516 Washington Street, Yountville. At a loss about what and where to plant in your own garden? Aren't sure of the factors that lead to a thriving yard? Home gardeners will examine their own garden's microclimates and receive tips and direction for choosing sites and plants suited to their particular locations and microclimates. To register, call the Parks and Recreation Department at 707-944-8712 or visit its 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.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.