As in much of California, Martinez enjoys a Mediterranean climate. You therefore have many options when it comes to gardening. When starting your vegetable garden in March, keep in mind that, although the daytime temperatures are warming up, evenings will still be a bit cool and you can expect only a little more than 3 inches of rain. If you have started your seeds indoors, March is the time to harden off the seedlings by allowing them a little time outdoors each day, and then extending that time every day for a week, prior to planting.
Carrots love the Mediterranean weather in Martinez and will thrive in the garden if planted in March. Ideally, the soil temperature should be 65 degrees; carrots will, however, be fine in cooler soil. Because carrots are root vegetables, you will need to dig down into the soil and remove any obstructions, such as rocks and old roots, prior to planting. Carrots are big drinkers, so water them often, especially if you should experience any warmer-than-normal days.
Spinach can be planted in March in Martinez, especially if you plant one of the slow-bolting varieties, such as Olympia, Jade, Symphony or Melody. You can grow and harvest those varieties right up until summer, in a partially sunny spot. Spinach likes rich, moist soil with a pH of 6.3 to 6.8. If the spinach leaves turn yellow it may be due to overly acidic soil. Spinach, like lettuce, is a pick-as-you-need it vegetable. Pull leaves from the outer portion of the plant and it will continue to produce more leaves.
Radishes are fast-growing and will enjoy the cool, moist mornings in Martinez. Because they generally mature within three to four weeks of planting, it's a good idea to stagger the plantings throughout the month of March to ensure a continual harvest. There are warmer weather varieties as well, so you may consider planting those later in the season. As long as your soil is well-drained, and you fertilize prior to planting, the radish should mature quickly. This is important, according to agriculturists with the University of Illinois, because radishes that stay in the ground too long tend to crack and split and to develop the "hot" flavor.
The artichoke grows wild in Mediterranean climates and is an agricultural staple of the Central Valley. In fact, California is the main supplier of artichokes to the United States. Although the weather in Martinez is not quite the same as that of the Central Valley, artichokes can thrive in the area. A member of the thistle family, the artichoke can grow quite large, so you will need to plant them at least four feet apart. The artichoke needs a lot of water in order to keep the head soft and succulent, so may require watering up to three times per week if the weather becomes particularly dry.
Cautions for Other Cool-Weather Crops
Although the temperature may be right for other cool-weather crops, Martinez's climate in March can be problematic for some common garden vegetables. Peas won't do well in March in Martinez as they are susceptible to powdery mildew and, because of the persistent fog in the mornings (the humidity can be as much as 94 percent). Brassicas such as broccoli and cauliflower also struggle in fog, drizzle and high humidity, and are susceptible to head rot and a plethora of other problems.