The month of July is a great time for gardeners and outdoor planters to sit back and enjoy the fruits of their springtime labor. At this point in the growing season, shade beckons and we’re inclined to leave any heavy-duty gardening or landscaping tasks until cooler weather returns in fall. However, given the intense heat and reduced precipitation levels typical of July, at least one gardening chore is inescapable this month—watering.
While providing moisture to plants might seem fairly intuitive, proper watering is one of the most commonly misunderstood aspects of gardening and landscaping. Sure, there’s the oft-heard guideline of providing one inch of water per plant per week. But this guideline is relatively meaningless when you factor in different soil consistencies (one inch of water will penetrate about 12 inches in sandy soil but only about four inches in clay), variations in temperature and humidity, the various microclimates present in any given landscape, and the particular watering needs of each different plant species.
Reaching the root zone
While there really is no one-size-fits-all formula for watering, it’s generally better to water plants deeply on a less-frequent basis than to water them lightly but more frequently. Frequent, light watering promotes shallow-rooted plants that are more prone to heat stress, wilting, and disease. Consider that you want the moisture to penetrate all the way to the root zone of the plant—or even deeper to encourage a drought-resistant root system. Depending on the plant, this is usually somewhere between six and 18 inches deep. It takes time for the water to penetrate to that depth, so don’t assume a quick spritz with the garden hose once a week will be adequate.
Deep watering is best achieved by positioning the end of a garden hose at the base of the plant and adjusting the water flow rate to a trickle. Leave it in place until the soil all around the plant is well soaked (you may need to move it to different points around the base for uniform coverage), and then move on to the next plant.
Save time and money with a soaker hose
If you have a lot of plants in need of moisture, watering them all deeply with a single hose may be impractical. In this case, a soaker hose may be a good solution. Soaker hoses have fine pores all along their length that weep moisture into the soil, making them ideal for watering rows of plants. You can also wind them through landscaping beds, encircling trees and shrubs at the dripline, which ensures that water will be directed to the youngest, farthest-reaching roots. (Note that a soaker hose and sprinkler hose are not the same thing. Whereas soaker hoses ooze water into the soil, sprinkler hoses are covered with small holes that spray water in a fine stream.)
Soaker hoses can be left in place above ground and concealed with mulch. Then all you have to do come watering time is connect the hose end to your faucet and turn it on. Avoid burying the soaker hose in soil, however, as the fine particles will eventually clog the pores and prevent water from seeping out.
One of the greatest advantages of watering with a soaker hose is that it cuts your water consumption considerably—by as much as 75 percent compared to a sprinkler.
Keep the foliage dry
In addition to driving up your utility bills, overhead sprinkling with a conventional oscillating or impulse sprinkler has another major drawback—it keeps plants’ foliage wet, which can predispose them to fungal diseases such as black spot and powdery mildew. Also, if you have plants with relatively tender foliage, droplets of water can act like tiny magnifying glasses and actually burn unsightly holes right through the leaves. As a general rule, try to water plants at their base rather than over the foliage.
Different gardeners may favor watering at different times of day, but watering early in the morning is usually your best bet. One reason is that the temperature is usually cooler and there is less air movement in the morning, so you tend to lose less moisture to evaporation than you would when watering in the middle of the day. Another is that if you do get any moisture on the foliage while watering, it will likely dry out more rapidly. In contrast, if you water in the evening and get the foliage wet, the moisture will tend to remain there all night long, providing the perfect environment for those aforementioned fungal diseases to flourish.
Watering container plants
Plants grown in containers require a different watering approach than those planted in the ground. The soil in containers tends to drain and dry out more rapidly (especially those hanging baskets), so a good daily soaking is usually necessary in July unless Mother Nature happens to oblige with a drenching rain. Spreading a layer of mulch over the soil surface in containers will help retain moisture, but you have to keep a close eye on the moisture level of the soil nonetheless.
Also, if you feed your hanging baskets and other container plants frequently, fertilizer salts may begin to encrust the soil surface. To help leach these salts out of the soil and prevent this buildup, it’s a good idea to thoroughly flush the container with (fertilizer-free) water until it runs through the drainage holes about every other week.