Are you caught up in that perpetual battle between high temperatures and watering? Let’s discuss your battlefield, weapons you have at your disposal and take a look at a few strategies that will help you have a winning yard.
Know your enemy
What exactly is the enemy you’re trying to fight? It’s the combination of high temperatures, dry soils, evaporative winds and all other factors that create drought-stress in your lawn and plants. Plants that become water-stressed will be more vulnerable to pests, diseases and winterkill than healthy plants.
Do some good reconnaissance in your yard. Know your soil type. Soil with more clay will be slower to absorb water and will hold it longer, whereas sandy soil will absorb water more quickly and dry out faster. Take a walk across your lawn. If your lawn is in drought-stress, your footprints will linger and the color of the grass will not be bright green, but a green tinged with blue or gray. Examine the structure of the trees, shrubs and other plants in your yard. Signs of under-watering may include wilted or curled leaves with crispy brown edges, especially towards the top and outer extremities, whereas plants that are over-watered may have older leaves that are yellow and wilted and new shoots may be pale green.
A good watering program is the best strategy. The importance of deep watering cannot be emphasized enough. Frequent, shallow watering encourages a shallow root system. When roots stay near the surface of the soil, they are at a greater risk of drying out. Deep watering encourages a root system that is well-developed with a better tolerance for periods of drought.
Lawns require 1 inch of water a week, which is best applied all at one time. In this heat, 10-15 minutes worth is just fumes, according to Amy Grandpre with the Yellowstone County Extension office, whereas 1 inch gets below the surface and into the roots. Grandpre is an advocate of the moisture meter as a simple and inexpensive way to measure the moisture in the soil. To measure water output of sprinklers, place small empty containers such as tuna cans at strategic spots in your yard. After watering, measure the level and adjust watering times accordingly. To prevent wasteful water runoff, do not apply water faster than the soil can absorb it.
Grandpre also recommends applying 2-3″ of water at a time on trees and shrubs. If the trees and shrubs are young (less than 4 years), apply water inside the dripline of the tree near the trunk. However, if the trees and shrubs are older, their root system is more extensive and watering from the edge of the dripline outwards is recommended. A deep watering may last 2-3 months depending on soil conditions and species of the tree. Aspen, birch, cottonwood, dogwood, maple, spruce and willow need more water than green ash, caragana, cotoneaster, lilac, pine and Russian olive.
Watering in the cool of the early morning, just as the sun rises is best. This reduces the amount of water lost to evaporation and ensures that the lawn and foliage of plants are dry before nightfall. Wet foliage during the night encourages fungus in lawns, mildews, rusts and other diseases.
Another strategy for maintaining soil moisture is to mulch. In lawns, leaving grass clippings on the lawn during hot weather will help prevent evaporation and water runoff. However, remove the clippings at the end of the hot weather to prevent disease. Or, instead of grass clippings, Grandpre recommends top-dressing the lawn with a thin layer (1/8″ to ¼”) of compost. This will also help prevent evaporation while adding organic matter to your lawn. The MSU Extension Service Guide recommends keeping your mower set 2-3 inches high during warm weather. Longer grass will help conserve water by keeping the soil cooler and minimizing evaporation.
There is no perfect watering schedule, but by being vigilant in monitoring soil moisture and observant as time passes and temperatures change, you and your yard will be victorious in the battle with the heat.