When it comes to summer vegetables, May is prime planting time. Nighttime temperatures are in the 50s, daytime temperatures in the 70s and 80s, and there is little chance of a late frost. By May the soil has warmed up, too, giving bean, squash and cucumber seeds the conditions they want for sprouting and growing.
So why am I writing about summer gardens in March? Because now is the time to get your beds ready for the summer season.
First job: remove weeds. Cut them down, pull them, chop them up, but get them out of your garden beds before they go to seed. Now, while the soil is damp from spring rain, is the ideal time to do this. Weeds are relatively small now so you can pull them easily. If you wait until the ground is dry, you will not be able to remove roots so readily.
While you're at it, if you have unplanted areas around your garden beds, keep them mowed before the weeds set seeds. If you don't, the wind, birds and insects may spread weed seeds to your vegetable beds.
Second job: add amendments. Many Napa County soils are largely clay. Clay soil absorbs and retains water well, but it lacks good aeration. Adding organic matter, such as compost, will help lighten the soil. Organic material allows the soil to form aggregates, or clumps, that enable root growth.
Compost, homemade or purchased, is an inexpensive source of organic matter. Spread a two- to four-inch layer over your garden beds. You can allow the compost to sit on top for a week or two—a good idea if the compost is still warm to the touch—or dig it in right away.
If you are gardening in raised beds or containers that you filled with purchased topsoil or potting mix, you may notice that the soil level has subsided several inches. Commercial formulations for garden beds are usually a 50/50 mix of clean, screened dirt and organic material such as compost. In contrast, ordinary garden soil is only 5 to 10 percent organic matter. Over time, soil organisms like earthworms and fungi digest the organic matter. You will need to re-fill these beds with additional material.
Third, you probably need fertilizer. Newly dug ground often lacks nitrogen, as Napa County soils are typically low in this primary plant nutrient. And if you are using beds that have been planted before, the previous crops used up some of the nutrients.
Garden centers carry a variety of fertilizers, some formulated for a specific use, such as vegetables or citrus. Packaged fertilizers always give directions for application. Don't be tempted to use more than the recommended amount; too much fertilizer can “burn” plant roots and pollute water run-off.
You may have access to manure from backyard chickens or rabbits, or bedding from stabled horses. Generally, such organic matter should be aged for several weeks or composted before using, as fresh manures can also burn plant roots. Do not use manure from carnivorous animals such as dogs and cats. Diseases that affect these animals can also affect humans.
Before you plant, set up your irrigation system and get support structures ready. In our climate, drip irrigation is the most efficient way to deliver water to plants without wasting it. Trust me, it is much easier to install a drip system before the plants go in the ground rather than after.Put up tomato cages and bean poles before the vegetables are planted.
Preparing the vegetable garden for summer can take some time, especially if you need to let compost or other organic matter age. But if your garden is ready for planting now, consider growing some quick, cool-season vegetables. After all, May is two months away, plenty of time to grow lettuce, radishes, beets, Asian greens, arugula or carrots. Why shouldn't your garden beds work just as hard as you do?
Workshop: Napa County Master Gardeners will conduct a workshop on “Ornamentals and Flower Gardens” on Saturday, March 21, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn about care and maintenance of ornamental shrubs and flowers in your garden. Discover how garden microclimates influence plant growth and success. Master Gardeners will also discuss hydrozoning and planting for seasonal color nearly year round, thus enticing more pollinators to your garden.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.