We have an unfortunate construction in the English language in that we typically say “I need to water my plants.” But thinking back to the Soil chapter, and the fact that all garden watering reverts back to what is good for the soil critters, we don’t water plants, we water soil.
As you learn more about healthy, alive, organic garden soils, you’ll discover that the place we need the water is to keep our vast populations of soil organisms happy. The leaves of most plants (short of rain-forest plants, but they aren’t appropriate to Southern California anyway), don’t do much as far as water uptake. It is the roots that can access the water, with the assistance of the soil organisms. We don’t want to drown the soil organisms (thus the wrung-out sponge analogy). Additionally, there are plants — most notably our squash family, cucumbers, and other fuzzy-leafed plants — that absolutely hate to get their leaves wet. These plants will rot away if you hose their topsides. Thus you must bend down and apply the water where it needs to go — at the soil surface.
It is not recommended to wait until your garden plants are droopy and pale to say they need water. Those visual signs indicate an extremely stressed plant, that has been neglected too far. It is very difficult for a stressed plant to regain full vigor — some can be stunted and never ever recover. In an in-ground garden situation, this phenomenon often results from improper planting techniques followed by abandonment. If the plant (or vegetable 6-pack or plant plug) was rootbound, and it was planted without fluffing out the roots, water will simply run off the exterior of this tightly wound rootball. For trees, a long-term rootbound problem might not be recoverable; you might have to replace the tree. For vegetables, pay attention as you plant them: don’t shove a geometric cube into the ground. Instead, gently fluff out the rootball with your fingers before you slide the plant into the soil. Water the transplants immediately, and in those first few days, don’t allow them to dry out. Apply the one-finger test many times around new plantings.
In the Community Gardens, we use signs to mark new plantings and newly-planted seedling beds. These spots need watering attention every time a gardener comes to the garden. Seedling beds are particularly challenging in our Southern California sun. Sometimes to sprout seeds, particularly in less-than-optimum soil conditions, you may need to use shadecloth and other sheltering devices to shield them from the searing sun. Another way to manage the water needs of seeds is to sprout them in pots in a more sheltered area, then transplant; all but root vegetables can be handled this way. Carrots are difficult to sprout, particularly if you have a soil-tension problem as described above. Carrots (and onions) need very consistent soil moisture to sprout, thus probably won’t work very well unless we’re having a stretch of foggy cool overcast weather. Carrots can sometimes be helped along by interplanting with radishes; the lusty radishes sprout easily and heave the soil upward, breaking the crust for the more delicate carrot seeds.
During the winter months, rainfall can have influence on watering patterns. More likely, the cool nighttime temperatures of our winter months have a greater influence. When soils are cool, moisture evaporates slower. Thus during the cool months, your garden demands far less watering. Simultaneously, the possibility of overwatering our natives, xeriscapes, and citrus is far greater. If we have had recent measurable rainfall, this probably means you’ll need to decrease your garden watering. (Turn off those automatic sprinklers!) Measurable rainfall can be determined very simply: by putting a bucket or pie plate outdoors in the garden in question. If a given storm puts an inch or so of water in your measuring device, that will affect your garden’s watering needs. But because we have erratic rainfall in any Southern California winter, you must become very diligent at using the one-finger test.