“How much should I water my plants?” is a question that has no simple answer. Attempts to provide simple answers have led to gross misconceptions on the subject of watering plants.
The biggest misconception about watering is that there should be a set schedule for this procedure. Not only does the frequency of irrigation change from one season to the next; it can also change from one week or one day to the next, depending on the weather. In overcast weather you can reduce by half, if not more, the amount of water you would apply in sunny weather.
The presence of strong wind can be just as desiccating, if not more so, than a blazing sun. Wind blows off the invisible layer of moisture that, given off during transpiration, normally hovers over and protects leaf surfaces. Awareness of the hazardous potential of wind is critical in newly planted landscapes, where the possibility of desiccation is always greatest.
Plants in breezeways or alcoves open at both ends are also candidates for rapid water loss due to wind. Rather than become frustrated with plants that struggle to grow in such conditions, it would make sense to plant more adaptable species. Succulent plants, for example, whether cactuses, euphorbias, jade plants or ice plants, are generally not as sensitive to wind as leafier plants would be.
A misconception of novice gardeners is that the condition or color of the soil surface is a good indication of when to water a plant. Nothing could be further from the truth. The surface of the soil can be beige and bone dry yet, if you only scratch the surface, you often find that the soil is quite dark and moist just below. Be aware of your soil type and do not be fooled by its surface appearance.
There are three areas where people water plants: containers, garden beds and lawns. Managing the watering of container plants requires the most vigilance. Not having any water to draw on other than what is in the container, these plants are most susceptible to wilt should the attention of the care giver wander. Regardless of the time of year, the experience of the waterer, or the cultural practices employed, container plants require a minimum of one weekly inspection in order to properly address their water needs. In July, three or four weekly inspections may be in order.
Watering in garden beds, on the other hand, is the easiest to control through proper cultural practices and plant selection. There can be enormous variance in the frequency of watering. Dry climate plants may go several months or longer without irrigation when planted in a garden bed, whereas they may require weekly watering when grown in a container. Deep watering in garden beds, since it encourages roots to grow more deeply, is accompanied by a reduction in watering frequency.
The biggest impediment to proper watering of lawns is the cost of water itself.
Unlike plants in containers or garden beds, it is virtually impossible to damage a Valley lawn by giving it too much water, so there is a temptation to leave the sprinklers on until soil saturation is reached. In five minutes or less, the spray sprinklers favored by most Valley homeowners will have put out as much water as the soil can absorb before runoff occurs. If you need to water 10 minutes a day, do it at two different times, such as at 4 and 7 a.m. Obviously, an automatic sprinkler system is desirable in such cases.
TIP OF THE WEEK: If you are not actively involved in testing the condition of your soil, you have no business making decisions about how much to water. Use a trowel or, better yet, a soil probe to learn how quickly your soil dries out at a two-inch depth. Most of the roots that take up moisture needed to meet the daily needs of plants are found at this depth.