The signs of spring are here: gaily blooming plum trees, the waxy petals of magnolia flowers, fields of brilliant yellow mustard adorning the vineyards, narcissus and daffodils everywhere, bees visiting manzanitas, and the courting behavior of birds. The signals and signs of spring are everywhere, and with lengthening daylight hours, we are drawn outside into the garden to begin planting our spring vegetable garden.
Early March is generally a perfect time to begin the process of preparing the soil, planting our starts, and seeding vegetables like greens, early broccoli, cabbage, Japanese greens, peas, beets, carrots, radish and onions. Right now visually we are cued to begin this process, but the prolonged cold temperatures have been daunting — both to our inclination to work in the garden and to plant growth. This precursor to springtime has been a challenge for many of us who grow a winter and early spring vegetable garden.
Cold air temperatures mean cold soil temperatures. Cold soil is not conducive for plants to grow or seeds to germinate, and the ensuing slow growth makes them vulnerable to being eaten by slugs, snails, or birds. Seeds may rot, or fail to germinate. Seedlings may freeze in the coldest areas.
Our existing winter vegetable plants are practically freeze-dried in many of our gardens and are not looking good. Many of our winter and spring vegetables have some degree of frost hardiness. Cold temperatures vary depending on where you live. Some areas are practically frost free, while others regularly endure winter temperatures with lows from the mid-twenties and even high teens.
Some factors that influence winter low temperatures are proximity to the coast and the moderating effects of the ocean.
Being on a slope, even a slight one, will also affect temperatures. Cold air is heavier and flows downhill. It tends to accumulate in the lowest valleys or low pockets. With the first fall frosts you can see the cold air’s actual dimension in vineyards by the vines frosting in a recognizable pattern of cold air pooling in a specific area.
Vines just a small degree higher in elevation may not initially be frosted at all. Even the coldest locations in our area may have a “banana belt” at higher altitudes.
The temperature at 1,000 feet may be as much as 10 degrees warmer in winter than the valley floor, influenced by warm air, which is lighter and so rises.
Even very cold hardy plants like kale, cabbage, broccoli, radicchio and chard can be damaged by days of freezing temperatures, particularly if it is also dry. They may just not grow. The lengthening days in early spring signal to many of these plants it is time to flower. Now is the time to replace them with young starts, or by seeding them.
What can we do to preserve what we have in our gardens until our new starts begin to grow, and how can we protect and encourage our new seedlings?
It seems odd to advocate watering in winter, but if the rains don’t come regularly, it’s a necessity. Poke your finger in the soil, or dig into the soil with a weeding tool or old screwdriver to determine if your soil is dry. If so, the plants will benefit from watering once or twice a week to keep soil evenly moist.