Watering is the most misunderstood cultural practice in lawn care. Improper watering is the most common mistake we encounter! Everyone seems to have their own ideas about it, especially with automatic irrigation systems. The increased use of these systems brings a tendency to use them as often as possible. This usually creates a variety of problems.
Before we get to how to properly water, let’s cover some basics about the typical grass plant and how it uses water.
How turf grass absorbs water:
Turf grasses come from the same grasses found in the Great Plains and other such grasslands around the world. These areas receive a certain amount of rainfall each year, but certainly not every day. They may go weeks without rain, and still survive. They do so by developing a fine and deep root system. These roots are designed to find moisture deeper in the soil as the soil near the surface dries out. The grass plant therefore relies mostly on its root system for moisture and not on the grass blades. Although there is some absorption of water and nutrients through the blades, they are mainly for food production through photosynthesis, and in transpiration of water up from the roots.
Bearing all of this in mind, we can see that it is more important for the soil to be moist rather than the surface and grass blades. Even though the improved turf grasses of today are far removed from the wild grasses of the plains, they still have similar water-use characteristics. Desirable turf grasses prefer moist soils to a certain depth, with a dry surface and leaf area. This provides them with the moisture needed for growth and an ability to withstand drought should it occur. It also keeps mold and fungus from developing on the succulent leaf blades where food is being made. These characteristics form the basis for proper watering practices.
General rules for watering:
Water requirements depend on several factors, such as soil texture, depth, grass types, sun exposure, slope, and water supply. There are several “rules of thumb” to follow:
1. You should think in terms of “soaking the soil” and not of “watering the grass”. This is the hardest thing for people to get used to. Wetting the grass blades for 10-20 minutes at a time will probably not wet the soil adequately, yet this seems to be the way most irrigation systems are set up.
If you have 6” of topsoil, it should be wet all the way through. If you have only 3-4”, the same holds true. The only difference is the amount of water required. We have your soil type and depth in our records. We use this as the basis for our recommendations.
2. Different areas of your lawn may have different water needs. An open, sunny area with a south facing slope will require more water than will a flat, shady section. As a matter of fact, we often see shady areas becoming weak and thin from applying the same amount of water that may be just right for a sunny area. If you’re having a problem with thin, easily uprooted grass in a shady area, and the soil is constantly moist, then it is probably getting too much water. Reduce watering there for better results.
3. Lawns need 1”-2” of water per week, depending on heat and rainfall, to stay green. If it rains 1” per week during the cooler parts of the growing season, (i.e. spring and fall), there is usually no need for supplemental irrigation. As the weather gets warmer, the need may increase to up to 2” per week.
4. 1” of water will soak approximately 6” of soil of average texture. Most home lawns on older, more established properties have 6” of soil. New construction seems to have less soil, and it’s usually of poorer quality, with less organic matter. 1” of water applied to these soils at once may result in water wasted into the subsoil.
5. It is better to water deeply and infrequently. Remember how the turf grass root system operates. A deep root system will find water days after it has been applied. The lawn will remain green and healthy. If the soil is less than 6” deep, then it’s best to break 1” of water into two waterings per week of ½ “ each. In the heat of summer, this may translate into watering every other day. This is usually the most frequent that we’ll recommend watering each week.
6. Daily watering will result in shallow rooted, disease prone, and weedy turf. Your lawn may stay greener, but if water is constantly being applied, then the roots will grow up toward the surface, causing excessive thatch development, less drought resistance, and greater incidence of disease. Also, weed seeds at the surface, such as those from crabgrass, will benefit from this constant moisture and are more likely to germinate and grow vigorously.
7. Don’t water any more often than every other day, even during the heat of the summer. Let the grass blades and the soil surface dry out for the day to promote more disease-free turf with fewer weeds. Even the hottest day will not completely dry out the entire soil depth. Let the roots do their job.
8. Apply the right amount of water. Apply enough water to soak the soil each time. This will usually be from ½” – 1” of water per zone/area each time that you water, based on how much top soil that you have. Any less will just wet the grass and any more will probably be lost to leaching before the roots can use it.
9. Water between the hours of 4am and 9am if possible. Research has shown that watering when the lawn is already wet from dew does not contribute any more to the incidence of disease than would occur under natural circumstances. On the other hand, extending the period that the grass is wet may increase chances of diseases. This is especially true with summer diseases, such as brown patch and summer patch.
Also, early morning watering conserves water by less being lost to evaporation. The soil is soaked just before the lawn needs it and the grass blades dry out at the normal time.
10. Don’t water if we’re getting enough rain. No need to water if Mother Nature is doing it for you. Anything less than 2 hours of steady rain doesn’t count. Short, heavy downpours usually run off before they can effectively penetrate the soil.
11. Too much water washes out the fertilizer. The major element in fertilizer that makes the lawn green is also very water soluble. Therefore, excessive amounts of watering may cause it to leach out before the grass can use it. This can also lead to groundwater pollution. Even though we use slow release fertilizer to help slow down this process, we need your help by watering properly.
12. Know how much water is being delivered to each zone. Use straight sided containers (tuna or cat food cans work well) or a rain gauge. Place one or more of them under the sprinkler and see how much water is delivered to that area in the time that you usually water. Compare this to our watering recommendations and adjust your watering time accordingly. Don’t be surprised if the zones all have differing times to get the recommended amount. These variations are why we can’t tell you how long to water.
13. Follow our instructions. We leave watering instructions every time we’re on your lawn. We may see something that requires different watering than what you’ll read here. For reasons already mentioned above, we will only tell you how much water should be applied, and not how long to run your irrigation.
When should you start watering?
There is no hard and fast rule for this, but most people start too early in the season, especially those with irrigation systems. The maintenance company turns it on in April or May, and it doesn’t stop until they turn it off in the fall. This is not good for the lawn.
Don’t start before the grass needs it. If you start seeing a blackish tinge as you look from the side, take a closer look at the blades of grass in that area. You may see that the blades are wilted, which give them a black look. Watering within a day of this will usually bring them back to green almost immediately. Also, if footprints, or other traffic marks, don’t disappear in a day or so, the grass may be too dry to recoil. You can also simply check the soil. If it’s powder dry in the top 6”, then it’s time to water.
If you don’t have the time to check your property, then follow the weather. If we stop getting 1” of rain weekly, and the weather is getting into the 80’s, then it’s time to water.
An even simpler guideline is don’t turn it on before Memorial Day, and turn it off after Labor Day. We may instruct you to water in our early spring application, but only if we don’t get rain. The irrigation should be turned off again after this unless unusually dry conditions prevail.
What if you can’t water?
Don’t worry. Turf grass is remarkably resilient, thanks to the extensive root system. As a matter of fact, many lawns that do not get any irrigation have more extensive root systems due to the constant need to search for water. They may go brown in the summer, but will usually recover completely when rain and cooler weather arrive.
A lawn without irrigation that is otherwise well-maintained will usually bounce right back year after year.
Here is what you can do to protect a lawn under drought stress:
1. Keep traffic to a minimum
2. Mow as high as possible.
We’ll help by checking for any potential damaging insect and disease problems. Lawns that are browned out are not necessarily dead. If a lawn is experiencing a drought condition, it will enter a state of dormancy. This is a self-defense mechanism to protect the vital parts of the plant. The blades are the most expendable, and therefore are allowed to die off. Once conditions become more favorable, the plant will send up new blades. This regrowth will usually take about 2 weeks of regular watering for the brown blades to grow out to mowing height.
Exceptions to the rules
1. Newly seeded lawns. Freshly seeded lawns need constant moisture to germinate. It’s not uncommon to water them 3 times daily, for short periods each time. This is only necessary until the new grass reaches mowing height and the root system develops. This usually happens around 4-5 weeks after seeding. Watering should then be throttled back to once daily, then down to every other day, as would be done for a normal lawn. Once the new lawn is 2 months old, it can be treated like an established one.
2. Certain disease situations. If the root systems have been damaged by disease, then it may be desirable to water daily, or even more frequently. This should only be done per our specific instructions.
3. “Hot” spots. Curbsides, septic tanks and leach fields, areas shallow to bedrock, and other unusual spots may require daily watering to keep them green. The rest of the lawn should be watered normally.