Your Garden Needs You
If gardeners will forget a little the phrase, "watering the plants" and think of watering as a matter of "watering the earth" under the plants, keeping up its moisture content and gauging its need, the garden will get on very well.
-- Henry Beston, Herbs and the Earth, 1935
We are suffering the clout of a once-in-a-decade heat wave on top of a little-discussed drought. If you desire to have one of those gardens that you envy in more ordinary times, this is when you must take the steps to keep your garden healthy. And right now that means well watered.
Watering home landscape and garden plants properly is one of the most misunderstood problems facing the typical homeowner and gardener. If landscape plants are water stressed during the summer, they may experience severe problems during the rest of the year, such as increased insect and disease susceptibility and decreased winter hardiness.
Knowing when and how much to water is a combination of art and science. Here I offer some guidelines.
Instead of developing a watering schedule based on calculations and fixed schedules monitor your garden daily to determine watering needs throughout the growing season. Consider your soil, your plants and recent weather.
For example, sunny areas dry out much faster than shady ones. Hot, windy weather dries out the soil. Plants that were recently planted (i.e. this season) require more attention and more frequent watering. Larger plants consume more water than smaller plants but need less frequent watering. Sandy soil holds much less water than clay soils.
Different plants in your garden will have different water requirements. For example, most landscape trees are still fine in this heat and drought. But dogwoods are under stress. They require a more moist soil and the dry soil weakens them and makes them more susceptible to anthracnose and other diseases. Hydrangeas are usually the bellwether for soil that is drying out.
Frequent, shallow watering keeps roots from growing deep and makes plants susceptible to drought. Over-watering can drown plants by filling up soil pores with water, leaving little or no oxygen for plant roots. Also, excessive watering leaches away nutrients and can contribute to groundwater contamination.
Developing plants need to be watered deeply, but less often, to encourage deep root growth. Water to a depth of at least 6 inches and then let the surface inch or two completely dry out before watering again.
That said, during periods of drought you will need to water more often. I’m seeing that most homeowners are not watering heavily enough. When you water, make sure the soil in saturated. Water the base of the plant and for most people, water for a longer time than you think is necessary. Sometimes a homeowner just sprays water over their garden thinking it is watered when the water hasn’t even penetrated the mulch layer.
At this time you can easily water a plant and when you’re done it is completely dry half an inch down in the soil. With the slightest slope, water will actually roll right off extremely dry soil. Sometimes you have to moisten soil and loosen it for the water to penetrate it. When you have plants on a slope, create a dam on the downhill side to hold in the water. Then water the plants several times in one watering session.
Here’s an important piece of advice, and you will learn a lot by doing it. After watering scratch the surface and see how deep the water has actually penetrated. Try it in several locations and environments. I bet many of you will be surprised to see how little water has gotten to the roots.
In the current drought the soil is extremely dry in many locations. Even when you do water deeply the water is quickly wicked off into the dry surrounding areas creating a condition where you will need to water more frequently than in times with ordinary rainfall.
Drip irrigation systems require a modest initial investment of time and money, but once installed, are convenient and conserve water. You can set up a drip system to meet the needs of individual plants precisely and then alter it throughout the growing season as watering needs change.
Sprinklers have the disadvantage of wasting water by watering paths and other open spots in the garden. They also lose water to evaporation and wind drift. Because they wet the foliage, sprinklers also can promote the development of leaf diseases. Hand watering is an extremely efficient use of water resources because it delivers water directly to the plants, thus eliminating waste, but it does take time.
