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.
When should you plant your garden tomatoes? Every year the seedlings arrive in nurseries and big-box stores by the middle of February. These tomatoes have been grown in a hothouse and do not like cold feet. They also prefer warm leaves, so don't put them out too early.
Wait until the soil temperature is at least 60°F during the day. Even without measuring I can tell that my soil is not close to that as the water coming out of my well is very cold. You can purchase a soil thermometer or use a compost thermometer if you have one. Measure the soil at a depth of two to three inches. The soil in my raised beds is currently just under 50°F.
If you have already purchased seedlings and the soil is too cool, then transplant the seedlings into gallon containers and keep them in a warm place until the ground warms. One friend kept them in his garage at night and dragged them out every morning until the soil warmed.
When the time comes to plant my tomatoes, I make sure the weeds are gone and the soil is smooth. Then I put cover the entire bed with clear plastic sheeting to keep the soil warm. I use pipes, boards and ground staples to keep the plastic flat. I determine how much room I need for each plant by placing my tomato cages feet up on the plastic. Then I cut a hole in the plastic inside each cage for the tomato. After I make the hole, I set the tomato cage aside but leave the plastic in place.
Tomatoes root easily along the main stem so if they are tall and lanky, dig a deep hole for them. Plant the seedling as deeply as possible, right up to the first set of leaves. Refill the planting hole with soil, lightly tamp it down, then water well.
Now place the cage around the tomato plant, pushing the legs right through the plastic and deep into the soil. Drive a stake into the ground inside the cage to stabilize it when the vine gets big. Square cages work much better than round ones. I have re-used some of my cages for many years.
As the plants start to grow, I protect them by wrapping the lower part of the cages with a couple of layers of Bubble Wrap. I secure it to the cages with clothespins. I also use a clothes pin on the plant tag so it stays with the plant. I have also used two-gallon plastic water bottles to protect small plants. I simply cut off the bottom of the bottle and place the whole thing over the plant.
Whatever method you use to water your tomatoes, be sure to water deeply. Ten minutes on a drip system is not enough. Once the plants are established, I usually water once a week. You can measure how deep the water has penetrated by pushing a piece of Rebar into the soil and noting where you meet resistance. Do not over fertilize, too much nitrogen encourages leaves not flowers. Once the flowers have begun to set fruit a dilute fertilizer or worm tea may be used every other week to keep plants healthy.
Tomatoes flowers are self-pollinating. Every morning I walk through the garden and shake the stems that have flowers on them. Bumblebees can do this for you using a technique known as buzz pollination or sonication. Their movement transfers the pollen from the anthers to the female part of the flower. Wind will also do this.
If you find a tomato you love and you want to save seeds, only harvest seeds from the healthiest vigorous and non-hybrid plants. Hybrid plant seeds will not produce the same kind of plant. Wait until the tomato ripens fully on the plant before you pick it then remove the seeds and spread them on a paper towel. Write the tomato's name and the year on the towel. Then let the towel air dry, store it in a dry place and save it until the following spring.
To start seeds, lay a piece of paper towel, seeds up, on the surface of a pot filled with soil. Water it and keep it moist. The seeds will grow through the towel to form roots. Reserve the strongest seedlings for planting.
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.
Spring and Summer Vegetables From Your Very Own Garden
By Pat Hitchcock, U.C. Master Gardener of Napa County
When should home gardeners start planting their spring or summer vegetable patches? A recent warm spell with near record-breaking daytime temperatures might have inspired you to consider getting some seeds and plants into the ground.
Your dreams of fresh produce might have been encouraged if you saw all the vegetable seedlings at local nurseries. However, nature is probably not finished with winter yet. Many of those nursery seedlings will not thrive if we have chilly days and nights ahead.
A look at the data can be enlightening. Here are the average monthly high and low temperatures for Napa: February, 62°F and 42°F; March, 67°F and 44°F degrees; and April, 71°F and 45°. But these temperatures are averages, which means that many days have lower lows or higher highs. The record shows that our area has a 90 percent chance of experiencing frost in January, dropping to a 10 percent chance in April. So there is still some chance of frost in the next eight weeks.
What does this mean for vegetables? Annual vegetables belong to several different plant families, but they may be loosely divided into two kinds: cool season and warm season. Cool-season vegetables grow best and produce the highest quality crop when average temperatures are 55°F to 75°F, and they usually tolerate slight frost when mature. In contrast, warm-season vegetables require long, hot days and warm soil to mature. They grow best when average temperatures are 65°F to 95°F, and they are damaged by frost.
March and April are much better for cool-season vegetables than for warm ones. Not only are the temperatures better suited to cool-season produce like broccoli, but they are anathema to warm-season vegetables. If we get frost, these tender plants would need to be protected from exposure that would otherwise kill them. The soil right now is pretty cold as well, and the heat-loving vegetables would not grow much until both soil and air temperatures warm up.
Fortunately, there are a lot of cool-season vegetables and many of them mature in 45 to 70 days. The list includes radishes, beets, carrots, lettuce, kale, spinach, Asian greens, broccoli and cauliflower. So you can plant these cool-season vegetables now and be finished with harvesting in May, in time to plan warm-season veggies. If you have limited garden space, this is one way to maximize production.
In Napa Valley, May is the first month when the average night temperatures hit 50°F, while daytime highs are 76°F on average. Over the summer and into early fall, daytime temperatures climb to the 80s and low 90s and nighttime averages stay in the 50s. These temperatures provide a four- to five- month growing season for the vegetables that need warm soil and warm air to thrive.
The long growing season is helpful because many warm-season plants need a lot of time to mature. In many cases, the part we eat is a fruit, botanically speaking. Melons, tomatoes, winter squashes and pumpkins are all fruits that we eat when ripe. Sweet corn, green beans and summer squash are immature fruits.
May is also the month when soils have warmed enough to plant warm-season produce. Although nurseries sell seedlings of many vegetables for you to transplant, several warm-season crops do better when started from seed planted directly in the ground. These include beans, squashes, cucumbers, melons and pumpkins. The minimum soil temperature needed for these seeds to sprout is 60°F. If you plant the seeds in cold soil, they will not sprout and may rot. In warm soil, the seed will come up readily, rapidly establish a good root system and grow well.
Is it time to plant vegetables? Yes, as long as you choose cool-season plants. Hold off on summer's heat-loving crops until the weather is warmer.
Workshops: U. C. Master Gardeners of Napa County will lead a workshop on “Growing Spring and Summer Vegetables” on Saturday, March 12, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa. Learn the requirements for success with summer vegetables from seed to starts. Topics include soil types and temperature; when to plant seedlings; how to water, fertilize, harvest and manage pests and diseases. On-line registration (credit card only); Mail-in/Walk-in registration (cash or check only).
The workshop will be repeated on Sunday, March 13, from 2 p.m. to 4 p.m., at the Yountville Community Center, 6516 Washington Street, Yountville. Register for the Yountville workshop at the Parks and Recreation Department at 707-944-8712 or on its web site.
Compost Workshops: on March 5 starting at 9 am and again at 11 am and Worm Composting on March 19 at 9 am. Preregistration is required. Find more information and registration links at our website http://ucanr.edu/ucmgnapa
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.
