As we move into the heat of the summer, we need to remember proper irrigation practices for our plants. It is just as easy to overwater as it is to underwater plants. And remember that irrigation practices differ among all different types of plants.
Value of Landscapes
Water requirements should always be part of your planning when planting anything new. For Nebraska it is best to go with more drought tolerant plants. We have been through many drought situations over the years, remember that when plant shopping, choose plants with lower water needs. Landscapes are necessary for many reasons including reduction in soil erosion and dust issues, reduced water pollution, reduced cooling costs in the summer due to shade, and being beautiful to look at and enjoy.
Water plants correctly all the time. It is easy to overwater plants, they don’t always need as much water as it seems they would. Water trees, shrubs, perennials, and turf all separately from one another, an irrigated turf is not adequate irrigation for a tree or shrub. According to the Nebraska Forest Service: “Newly planted trees should receive no more than an inch of water a week during the growing season. Don’t water more than two or three times a week. Running automatic irrigation systems 20-30 minutes daily will severely damage the root system and can kill a tree.”
Watering Trees and Shrubs
For trees and shrubs, use a slow trickle from the hose or a sprinkler. Let it run for about an hour for older trees. If it is a smaller or newly planted tree, it won’t need to be irrigated as long, only about 15-30 minutes each time. Tree irrigation should be done once every week or two, depending on how hot and dry it is. Irrigation for shrubs is similar to trees, but they don’t need to be irrigated as long each time. Use the screwdriver method to determine the need for irrigation. Push the screwdriver into the soil prior to irrigating. If the screwdriver goes into the soil easily, you don’t need to irrigate, if it is difficult to push into the soil, the plant needs irrigated. You can use that screwdriver after irrigation to determine that you did get enough water into the soil profile for the roots of the plant. The majority of tree roots are in the top 12-18 inches of soil, shrub roots are about 8-10 inches deep. Check to see that your screwdriver gets mud on it that deep into the soil profile after irrigation to ensure correct moisture. The Photo above is from John Fech, Nebraska Extension Educator and it shows a screwdriver with mud on it, showing good irrigation.
Also, maintaining mulch around trees and shrubs helps retain moisture. Use organic mulch, 2-3 inches deep in a flat ring around the plant.
Watering the lawn
As for lawn irrigation, the bottom line is to keep the roots moist, not soggy or dry, and water to the bottom of the roots. Watering regularly through most of the year and stopping for vacation or in drought is more of a stressful situation to the lawn than not watering at all. Maybe ask a neighbor to help irrigate your lawn while you are on vacation (and be sure to return the favor!). A good way to manage irrigation in the lawn is to start by shutting off the automatic sprinklers and only watering as needed. Watch the lawn for signs of drought stress to determine when to water and avoid drought by monitoring soil moisture with the screwdriver method. Turf that is drought stressed will have a blue hue instead of the normal green, the leaf blades may be rolled or folded or you may notice that your footprints are very visible in areas where you have walked. Kentucky bluegrass lawns can be allowed to go dormant, while tall fescue lawns will usually not recover if lawn watering is discontinued during a drought.
Plants and Pests with Nicole 