By Heather Dooley and Pat Hitchcock, UC Master Gardeners of Napa County
The recent rain and cool weather have given us plenty of time to pore over all those seed catalogs looking for a new vegetable variety to try or reordering seeds for our favorites. It's time to start planning your summer vegetable garden (although it's not planting time yet).
Fortunately, we live in an area with a Mediterranean climate, characterized by long, dry summers and mild, rainy winters. As a result, we have two cool seasons annually for gardening, one in late summer and early fall and the other in early spring. Our warm season typically starts in late April when the soil is warm enough to plant tomatoes. Now is the time to start planning for that warm season.
You can start your own warm-season vegetables now in pots. Tomatoes, peppers and eggplants are easily started from seed indoors. These vegetables require warmth to germinate so it's a good practice to put seed-starting trays on a heat mat.
All seeds need the correct temperature and moisture to germinate. But after they sprout, light becomes all important. Put baby seedlings in a sunny spot by a window or, if using a grow light, keep the light about 1 inch above the leaves to prevent spindly, weak plants.
If your seedlings do get leggy or aren't dark green, they need more light. Keep soil moist but not soggy and use a half-strength liquid fertilizer once a week. In about six weeks they will be ready to plant outside.
Be sure the area where you intend to plant your seedlings gets enough sun. Six to eight hours is the minimum for most vegetables.
Do you have a plan for irrigation? And have you examined your soil? Is it nice and crumbly, like a piece of chocolate cake? Or is it waterlogged clay? Clay soil holds micronutrients but typically needs to be amended with compost to lighten it, so it has air pockets for the nutrients to cycle.
Have you been adding organic matter to feed the soil microbes? Soil is alive. It has both macroscopic organisms (the ones we can see), such as earthworms, aerating the soil and decomposing organic matter and also microscopic organisms such as bacteria and fungi.
Mycorrhizae are fungi that live in association with the roots of plants. These fungi collect nutrients for the plants in exchange for carbohydrates. It's a wonderful example of life forms helping each other. There's a whole conversation going on underground in healthy soil.
Don't neglect weeds. Most soils have a large amount of weed seed just waiting for the right conditions. Weeds compete with your vegetables for water and nutrients. Controlling them is a constant part of gardening but can be managed by depriving the weeds of water and light. Mulch your beds to exclude light, water only where necessary for your vegetables and disturb the soil as little as possible to avoid bringing up a new crop.
Plant healthy transplants at the right time to encourage growth and to out-compete weeds. Chemical weed controls are not recommended in a vegetable garden and not needed in most situations.
Now that you have a sunny spot with great soil, access to water and no weeds, what do you want to grow? Ask yourself why you are gardening. Is it for flavor, to save money, to harvest organic produce or to have access to unusual produce varieties?
It's tempting to want to grow everything, but properly spaced plants will be healthier and more productive than plants spaced too closely. Make a planting plan on paper. Think about the size of the vegetable when full-grown and how long it will be in the ground. An indeterminate tomato plant will eventually need almost nine square feet of growing ground and will need to be supported with a strong five-foot-tall cage. Can you stagger plantings for a longer harvest season?
It is better to grow fewer plants well than to have a large vegetable garden that you can't take care of. Gardening is work and therapy, and you get tomatoes, too.
See complete list of upcoming events on our website calendar http://napamg.ucanr.edu
Free Talk, 1 hour: “Growing Summer Vegetables” at the Napa Public Library on Thursday, March 7, from 7 p.m. to 8 p.m. Learn what you can grow in the summer, what to plant and when, and how to have a harvest all summer long. No registration required.
Workshop, 2 hours: “Growing Spring and Summer Vegetables” on Saturday, March 9, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Do you want nutritious, easy-to grow and utterly fresh food from your garden this spring and summer? Learn what the garden needs to successfully produce spring and summer vegetables from seeds and plant starts. In addition to growing basics and hands-on activities, this program includes watering, fertilizing and harvesting tips, with a dash of Integrated Pest Management for pest and disease control. The delight of growing your own groceries is matched only by savoring them at harvest. Online registration (credit card only); Mail-in/Walk-in registration (check only or drop off cash payment).
Workshop, 2 hours: “Summer Vegetables” on Sunday, March 10, from 1 p.m. to 3 p.m., at Yountville Community Center, 6516 Washington Street, Yountville. Get tips for growing your own summer vegetables. Learn some basics, get keys to success, and do hands-on activities to learn about new varieties and review old favorites. Enjoy healthy vegetables taken straight from your garden to your table. The delight of growing your own vegetables is matched by savoring them at harvest. Online registration or telephone the Parks & Recreation Department at 707-944-8712.
Demonstration garden update: UC Master Gardeners of Napa County have begun the process of re-establishing a demonstration garden in Napa Valley. For further developments, please visit the Demonstration Garden link on our website ( http://napamg.ucanr.edu/).
Master Gardeners are volunteers who help the University of California reach the home gardening public with research based gardening information. U. C. Master Gardeners of Napa County (http:/napamg.ucanr.edu) 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 Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County./span>
When clients bring sickly plants to the Master Gardener help desk, we ask about conditions in their garden. How often do they water and what method do they use?
For every inch a plant grows, there is probably an inch of roots holding it in the ground and nourishing it. In my experience, clients often water less than plants need. Ten minutes with a drip system three times a week is usually not enough.
When I was training to become a Master Gardener, our class studied how fast water drains through soil. Dry soil has tension; water moves around the surface until it can work its way into the soil. For a demonstration in class, several large tubes were filled with different soil types: sand, mulch, clay, loam and gravel. We watched water work its way down through each soil type and learned that each level had to be saturated before the water moved to the next level.
The same is true in your soil. For deep roots, water deeply.
Many vegetables develop roots that go three feet deep; several, like tomatoes, can have four-foot-deep root zones. Consequently, that is where the water needs to go.
Last year, Napa County Master Gardener Ray Sittig made drainage slits in gallon-size cans, then sunk a can in the soil alongside each of his tomatoes. He filled the cans with water twice a week, and the water slowly seeped into the soil.
Hardpan is another potential problem. Your soil's hardpan is the layer below the topsoil that is impervious to water. In my garden, it is a couple of feet beneath the surface. Hardpan was formed by clay deposited during flooding. Most of the top couple of feet of soil has had mulch, compost, fertilizer and other amendments added. Water penetrates easily but stops when it reaches the hardpan. I often push a length of rebar into the soil to see how deep it goes before hitting hardpan. In my vegetable garden, I continue watering until the rebar goes in easily.
When preparing to build raised beds, some gardeners dig the soil below the bed and work compost into the soil to break up the hardpan. Then the raised bed with its improved soil is built on top.
When I plant tomatoes, I place plastic on top of the soil to conserve water. This barrier keeps moisture in the soil, warms the soil and encourages growth. I have also used clean cardboard, cutting holes in it for the vegetable seedlings.
After planting, apply mulch to the soil surface to retain moisture. My habitat garden, which I don't irrigate, has a heavy layer of mulch. Because of that moisture-retaining barrier, it is still easy to pull weeds. One reason to remove weeds is to keep them from taking water from the plants you want.
If you have a plant problem, bring it to the Master Gardener help desk (see hours below). During the summer season, Master Gardeners also staff a help desk at farmers' markets and garden centers around Napa County. Please bring your plant sample in a plastic bag.
Workshop: Napa County Master Gardeners will hold a workshop on “What's Bugging You?” on Saturday, June 18, from 9:30 a.m. to 11:30 a.m., at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Understanding pests and blights that affect your vegetables is key to managing them. Squash that doesn't grow, tomatoes with peculiar markings, artichokes full of earwigs, plants that fail to thrive − all these and more will be discussed. Bring your own problems to show and tell and learn how Integrated Pest Management techniques can help. Mail-in/Walk-in registration (cash or check only). On-line registration coming soon.
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.