A lawn exhibiting symptoms of drought stress.
S.D. Drought: Lawn & Garden Impacts
The most recent U.S. Drought Monitor South Dakota Map, shows that over 90% of South Dakota is already under abnormally dry to extreme drought conditions. While some areas of the state did receive some rain over the last two weeks, showers were very spotty with many areas not getting any rain at all. Many people had patchy areas of dead grass in their lawns this spring and now many lawns consisting of cool-season grasses like Kentucky bluegrass, perennial ryegrass or fine fescues are turning brown and going dormant.
Many communities have already or will be imposing watering restrictions. Since the drought the last couple of years lasted so long, many people just gave up watering entirely. Or, for some people, it is just not practical to water a large lawn, particularly if they do not have a lawn irrigation system installed. Many people choose not to water their lawns, knowing that it will likely go dormant and turn brown during the heat of the summer, expecting that it would green up again in the fall.
In most years, lack of watering is not a problem, but when no rain falls for several weeks in a row, permanent damage can occur to cool-season grass lawns. If the crowns, where the growing points or buds of the individual grass plants are located get too desiccated, they will die and not regrow. They don’t need much moisture to remain viable, just two tenths of an inch of rain or irrigation every two to three weeks is enough to keep those crowns alive and allow them to regrow with heavier rain or irrigation later in the fall.
Drought-Stressed Lawn Management
Fall lawn rejuvenation.
Typically, when temperatures cool in the fall we also get rainfall to reinvigorate lawns and other plants. However, for many lawns last fall, this did not happen. The grass plants went into winter and freezing temperatures under water stress. These stressed plants were also not able to store up as many food reserves to help them get through the winter months. The lack of snowfall also left these grass plants exposed to drying winds much of the winter, further damaging the individual grass plants.
Over-seeding, renovation, and weed control.
If your lawn did not green up this spring even though you had rain or you irrigated, you may need to consider over-seeding or renovating the lawn this fall. Also, If it appears that your lawn is mostly weeds, this may be another reason to consider total renovation of the lawn. This generally involves a lot more preparation of the seedbed than just re-seeding a few bare spots. A non-selective, non-residual herbicide, like glyphosate, can help get rid of the old weeds and grass to help you get off to a clean start. Keep in mind that the herbicide will not be very effective until the weeds are actively growing – it is not likely to do much good now if the weeds are also stressed and not growing much with the drought. Generally, it is better now to wait until fall to try to renovate an old lawn. Generally temperatures will be cooler, moisture conditions are better, and warm-season weeds like crabgrass will be slowing in their growth and die with the first freeze.
Seeding and watering.
Whenever you decide to plant your grass plants, either by over-seeding or renovating in the fall, it is critical that you keep the seedbed moist until germination of the grass seed is complete. This can often take three weeks, particularly for some species like Kentucky bluegrass. You need to be patient and persistent with light, frequent irrigation or watering to keep that top inch of soil moist until the new seedlings emerge. Then you should decrease the frequency of watering and water more deeply instead.
Mower height adjustment.
Generally, the best way to keep your lawn looking green this summer includes more than just lots of watering. First of all, raise your mowing height. If you allow your grass to grow taller, it will develop a deeper root system so it can take up more water that might be available deeper in the soil. Mow frequently enough so that you do not remove more than 1/3 of the grass plant’s height. It is OK to leave the clippings fall on the lawn, particularly if you use a mulching mower. Those chopped up clippings act as mulch to help cool the soil and grass plants and as the clippings break down, they recycle nutrients to the soil. Make sure to keep your mower blades sharp. Dull mower blades make ragged cuts to the grass leaves, allowing them to lose more moisture. Fertilize in moderation. Most people can get by with 1 to 2 pounds of actual nitrogen per 1000 sq. ft. per year with the most of that applied in the fall. Finally, water infrequently and deeply. The objective is to saturate the root zone, usually down to about 4-6” deep. Then, that root zone should be allowed to dry out somewhat before you water again. In a well-drained soil, this could mean watering once per week, applying about 1” of water at a time. If the soil is clayey or slow to absorb water, you might need to break up the irrigation so that you may apply ½” of water twice a week. Avoid watering every day or even every other day. This tends to keep the very top of the soil profile saturated which discourages root growth down deeper in the soil and also excludes oxygen from the upper layer of the soil which leads to thatch accumulation and potentially disease problems later on.
Warm-season vs. cool-season grass performance.
There are of course other options to having a cool-season grass lawn. Utilizing native warm-season grasses and other plants in your yard, instead of trying to maintain a lush green lawn may be another viable alternative that can be aesthetically pleasing and also benefit wildlife, butterflies and other aspects of the environment. Buffalo grass, a warm-season lawn grass that grows well in the Summer (pictured at left next to mixed bluegrass on right in July) can tolerate hot and dry weather better than cool-season grasses. However, it is slow to green up in the Spring (buffalo grass on left compared to mixed Kentucky bluegrass lawn in early April pictured at left) and quickly turns brown in the fall when temperatures drop, usually in October. Broadleaf weed control in buffalo grass can also be more challenging in that the typical herbicides used for controlling weeds in most cool-season grasses can cause some damage to buffalo grass.
Summer: Buffalo grass (left) vs blue grass (right) in July.
Spring: Warm-season (left) vs cool-season (right) grass in early April.
Vegetable Garden Management
Vegetables can also become severely stressed if they are not provided with supplemental irrigation during dry periods. Other plants like perennial flowers, shrubs and even trees are now suffering from these dry conditions too. Providing supplemental irrigation when needed while also conserving water where possible is a worthy goal of any gardener. Drip irrigation is a good option to consider for the vegetable garden as well as for plants in your landscape. Drip irrigation systems can be set up easily using ooze hoses, drip tape or drip tubing. Just place it along the row while the plants are still young. Then, when the soil dries out, turn it on and it will water just along the row and not the whole garden. Since the water just oozes or slowly drips out of the tubes or hoses, spraying water up in the air means much of it will be lost to evaporation before it even gets to the plants’ roots. There are also other benefits besides just saving water too. It also helps to reduce weed growth in between the rows and keeps the foliage and fruit dry to reduce disease problems. Placing the ooze hoses or drip lines beneath mulch also helps further reduce water loss by shading the soil and reducing evaporation.
Drip line next to onions.
Leaf lettuce growing in black landscape fabric with drip tape.