Drought Conditions Stressful On Lawns And Other Plants

 

 

 

The most recent US Drought Monitor map for South Dakota, released July 19 shows that about 43% of South Dakota is already under moderate drought conditions with an additional 26% abnormally dry. While some areas of the state did receive some rain over the last two weeks many areas received less than half inch. Dry conditions last fall coupled with a lack of snow this past winter and a dry spring could mean many people will notice that their lawns did not green-up like they normally would and then quickly turned brown following the exceedingly hot temperatures earlier this spring and again during the first part of the summer. Particularly if they mostly have a cool-season grass like Kentucky bluegrass, perennial ryegrass or fine fescues. Many of these lawns dried out last summer and fall, did not recover in the fall, and never had the chance to adequately prepare for the winter. The result is that some lawns had fairly large dead patches of dead grass this spring. Other plants like perennial flowers, shrubs and even trees were slower to emerge or leaf out and are now suffering drought stress because of the hot and dry conditions.

 

 

Many communities have already imposed watering restrictions. Since the drought last summer and fall 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 they will likely go dormant and turn brown during the heat of the summer, expecting that they would green-up again in the fall. In most years, that would not be 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 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.

 

Typically when temperatures cool in the fall we also get rainfall to reinvigorate lawns and other plants. But for many lawns last fall, this did not happen. The grass plants went under freezing winter temperatures, already 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 grasses exposed to drying winds much of the winter, further damaging the individual grass plants.

 

Most people apply fertilizer to their lawns in early spring, expecting that this will help their lawn green up. However, that only works if the fertilizer is watered or rained into the turf and there are live grass plants there to respond to the extra dose of nitrogen provided by the fertilizer. In fact, if a lawn is in bad shape with much of the grass slow to show signs of growth this spring, it would probably be better to hold off on fertilizing until the grass begins to show a fair amount of new growth. This is especially true if the lawn was fertilized last fall. Then the first spring application of fertilizer should likely be delayed until mid- to late-May.

 

 

 

Dead turf areas.

 

If your lawn did not green up this spring or has turned brown and you have had rain or you have been running your irrigation system you may need to consider over-seeding or renovating the lawn. First of all, check to see if you do have live but still dormant grass plants in your lawn. Try using a stiff rake to rake over brown areas. Don’t use an excessive amount of force, but enough that you will remove loose material like old, dead grass blades, and dead grass plants. If after you rake you are essentially down to bare ground, there is likely little hope that the area will green-up again on its own. If you can still see that there are distinct plants, present that still seem to be well-rooted in the soil, then there is a good chance the lawn will recover. You may still want to do some over-seeding to get more grass plants established. If you don’t, you are more likely to see that thin turf filled in with weeds by summer.

 

Once you have raked over the bare areas and removed the loose material, you should have a fairly well-prepared seed bed. Pick up some fresh grass seed from your local garden center, nursery or hardware store and spread it according to the rates listed on the seed package. Be sure to take a look at the seed tag or label that shows what is contained in the seed package. Kentucky bluegrass, often in a mixture of varieties, is likely the best option for a sunny location. Perennial ryegrass may also be a component of the grass mix but this grass is often less hardy than Kentucky bluegrass, particularly in more northern areas. Tall fescue is another potential grass in a blend but it may also be less hardy and also have a coarser texture than many people prefer in their lawns. If you are seeding a shady area, look for a seed package that says they are for shade. These will likely contain a blend of chewings, sheep, fine or creeping red fescues. Beware of grass seed mixes that contain mostly annual ryegrass. While these will be much cheaper and provide faster germination and green-up, the plants will not survive the winter so you will be right back where you started next spring.

 

If major areas of your lawn are dead or you find that your lawn is mostly weeds you may want to consider total renovation of the lawn. This generally involves a lot more preparation of the seedbed and perhaps the use of a non-selective, non-residual herbicide like glyphosate. Keep in mind that the herbicide will not be very effective until the weeds are up and actively growing. As temperatures climb this spring, warm season weeds will also begin to germinate and could cause considerable competition with newly emerging grass seedlings. Consequently, it is often better to just wait until fall to try to renovate an old lawn. Generally temperatures are cooler; moisture conditions are good and warm season weeds like crabgrass will be slowing in their growth and die with the first freeze.

 

Whenever you decide to plant your grass plants, either by over-seeding or renovating this spring or later 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, and provide 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.