How to Water Wisely

  • Difficulty Rating: Beginner
How to Water Wisely

When I studied horticulture in college, our instructor reminded us repeatedly that learning to water is one of the hardest parts of gardening.

He was right. Although we occasionally have to set automatic irrigation to water by the clock, rarely is this the best way to keep our plants properly watered. Unfortunately, the calendar doesn’t have the capacity to review everything we need to consider before applying more precious water to our gardens.

The first step toward using water wisely is to create and install gardens using plants that have similar needs. For instance, don’t plant a soggy, bog-loving plant like skunk cabbage adjacent to a cactus originating in a bone-dry desert. Instead, group plants that like soggy-boggy soils into exactly that kind of environment. And put the cactus in a spot where the soil is well drained and sandy – like a desert.

Once your garden is filled with plants with like-minded neighbors, be sure to evaluate how your soil behaves. Is it sandy, loamy, clayey or something in between? Sandy soil will drain fast, holding very little water for plants to access over time. Loam soils will hold more water longer than sand. And, clay will hold onto water tightly – until it dries out and becomes brick-hard. Knowing how well your soil holds water will enable you to better monitor when it is reaching a drying point and really needs more water applied to it. Although you can invest in expensive moisture-monitoring systems that can even fire off irrigation at the ideal moment, most gardeners will do well to use the finger-test to check for watering requirements. Don’t wait until your plants burn up and crash to begin watering.

Try using the finger-test method by simply sticking your finger deeply into the soil near your plant. Even if the top few inches are dusty and dry, if the soil below (in the area where plant roots are growing) is damp or wet, you may be able to wait another day before irrigating. If it is getting dry below the finger point, it’s probably time to apply some water.

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When adding water to your soil, take the time to apply it directly to the soil via slow, gentle, deep soaks. When water is applied rapidly and in a harsh stream, gardeners are more likely to damage plants. And, water is more likely to simply run off rather than saturate down to plant roots. Run off water is a waste, plus it can take precious topsoil, mulch and nutrients away from plants as it erodes the soil in its path. How often your beds or containers will need water will vary and how long it takes for you to properly wet the soil can vary.

Usually, newly planted containers won’t dry out as fast as older plantings, which become root-bound and therefore less able to hold water over time. Take care to water all container gardens regularly, and be sure to water them sufficiently so that the water passes through all of the container soil before passing out of the drain hole at the bottom. If your container plants are root-bound, you may need to run water through the container multiple times during the day to give the plants enough water.

When applying water to your garden beds, try to deliver the water as closely to the plant as possible. Drip irrigation and soaker hoses deliver water from the source directly to the soil. When using sprayer and sprinkler systems, we lose more water to evaporation in the air. Once you do apply a slow soak to your garden bed, turn off the water and let the garden rest for about 15-30 minutes. Then try the finger test again to see if you need to apply more or less irrigation to get a well-saturated bed. Once you do this a few times, you should begin to get a feel for your garden’s usual watering needs.

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Even in the Pacific Northwest where I garden, we do experience drought periods. And, for us, these droughts can be deceiving. Come summer, it may drizzle a bit one day, but the rainfall never amounts to enough to saturate the soil down to the root zone. In Virginia, where I grew up farming, we would have heavy summer downpours. But, if the clay was already dried out, much of the water simply washed away. So, again, even if it appears to be raining, keep up with your finger tests and apply water as needed. And, don’t over-water. Overlay saturated soils can suffocate plant roots by denying them access to the oxygen they need from the soil. If your irrigation is set to fire off during heavy summer downpours, take a moment to hit the over-ride button and save that water (and money) for when you need it later.

To help your soils hold more moisture and reduce your watering costs, be sure to apply composted mulches to the tops of your garden beds. The organic materials in compost have significant water holding capacity and will help meter out the water that travels downward into the soil to the roots over time.

And, remember, the first contact roots make with the soil is critical to a plant’s future health. Be certain to pre-water and drain containers before filling them with plants. And, whenever planting in the garden or in a pot, be sure to water all new plantings immediately after installing them.