by John C. Fech

July and August is the time period most commonly associated with watering the lawn. This is odd, as there is just as much need for irrigation in spring and fall, just in lesser amounts... maybe it's the heat that brings out the interest in watering. As you are getting set to blow out your customers' systems, take some time to make sure they are operating as they were designed. Many of your clients will be interested in an irrigation audit, outlined later in this article. An audit is good for the customer because it saves them money on irrigation bills, good for the environment because it reduces wasted water.

One of the keys to effective and efficient watering is to learn to recognize wilting in turf plants. Applying water just prior to the onset of wilting helps you get the most "bang for the buck" from each run of the sprinkler system or turn of the faucet. It is relatively easy to recognize wilting on a houseplant: the leaves droop and the stem may wither, and the whole plant may have a "dull" appearance. Because they are much smaller and thinner than houseplants, it is more difficult to recognize drought stress in turf plants.

The overriding principle of irrigation efficiency is to soak the ground to a half-inch or so beyond the bottom of the plant's roots. Any more than this is wasteful, and less causes the lower roots to slough off. Keeping the extra half inch moist allows a suitable medium for deeper growth, which, of course, is highly desirable.

Keep the differences between the turf species in mind when considering seasonal root growth. Warm-season grasses (St. Augustine, Bermuda, zoysia) are shallow rooted in spring and fall and quite deep in summer. Cool-season grasses (Kentucky bluegrass, perennial ryegrass, tall fescue) are just the opposite-deep in spring and fall and shallow in summer.

The most critical factor in watering is uniformity. This is paramount. Making sure that the entire turf area receives the same amount of water will save water, save money and make the green space more attractive.

Perform a simple audit on your client's system by placing an empty tuna can 2 feet away from each head and one in between each head. Run the system for 15 minutes and measure the water in the cans. While the test is being conducted, look for problem heads, clogged nozzles, heads that don't turn, heads that spray driveways instead of turf, heads that are out of line, etc. Multiply the amount collected by four to calculate the amount delivered per hour. Compare the volume in each can. Are some more than others? You may find that a brown spot in a lawn is near a head that puts out more water than the others or less than the others. If you haven't checked it out lately, the odds are good that at least one of them isn't working properly, or at all. Make repairs and replace heads as needed. Water savings are realized when theequipment is repaired, because the common tendency on the part of the customer is to water the lawn until every part of it is green. This means that if Part A receives half an inch, and Part B one fourth of an inch, most homeowners will water both areas until the desired effect is achieved-a green lawn. In this case, Part A is getting twice as much water as needed, a waste of water and money.

It's obvious if you think about it: turf needs more water during periods of high temperature. When temps reach the 90s and stay there for a few days, cool-season grasses start using more water. At these temps, most bluegrass lawns are going to need 1.5 inches of water per week, either from rainfall or from irrigation, while tall fescue can usually get by on about half that amount. That old, empty tuna can will tell you how much water has been applied. Wind speed is another factor to consider. The more wind, the more water loss.

If you want to get precise about it, check with your local water utility, and ask them for daily evapotranspiration (ET) rates. This is the average amount of water lost to evaporation and transpiration in the last 24 hours. In summer, ET rates vary between .15 and .30 inches per day. If .20 has been pulled out of the grass plants each day for a week, that adds up to a little less than 1.5 inches that needs to be replaced. The lawn's roots are likely to be shallow, so it's best to put that volume on in two or three applications.

I'm often asked, "When is the best time of day to water?" This question is usually asked by turf managers who have heard rumors about certain times and possible pitfalls. So, let's examine each time period and look for the pros ands of each.

First, let's look at nighttime or 10 p.m. to 6 a.m. This time is attractive to some, because they know that evaporation is much reduced at night during the darkness. Unfortunately, most foliar diseases thrive on long periods of leaf wetness, so this is probably the worst time to water.

So, how about if we back it up a bit and water from 6 p.m. to 9 p.m.? No real advantage here; evaporation losses will be significant, and the grass will probably not have enough time to dry off before darkness, and the potential for fungus remains.

All right, let's try noon to 6 p.m. Well this is a period of high evaporation and high wind speed. true, the grass blades will dry thoroughly, which will decrease the chance of foliar pathogens but homeowners who water in the afternoon typically only get a third to a half of the water to the grass plants; the rest ends up in the atmosphere, on the street and the neighbors yard. this leaves us with the morning hours, 5 a.m. to noon. There are no strong disadvantages and only pluses with this time period, as normally light morning winds and soft sunlight rays help keep most of the water on the lawn, and the grass has the whole day to dry off, discouraging disease. This is the best time of day to water; instruct your customers accordingly.

Do you remember running through the sprinkler on a hot, summer day? Other than the pounding the lawn took from the kids' feet, this was a good thing for the turf, as well as for people. The sprinkler running in the afternoon has a cooling effect on the grass, so cool the sod with a technique called syringing. Just a few (five to eight) minutes or so is all that's really necessary. The water is cool-about 60 degrees or so. The same cooling effect takes place for your lawn. The cooling effect is coupled with stress reduction through the reflection of light energy while the grass blades are covered with a water film. Green spaces that are syringed when the air temps climb into the 90s are less likely to show symptoms of summer patch disease. Be sure to stay on track with regular watering, as syringing doesn't do much for the roots.

Take a good look at the landscape. Do your customers have trees and shrubs growing right in the middle of their lawn? If so, it's time to help them redesign their landscape, separating the grass from all of the other plants. Think of turf as a part of the landscape unto itself. It should be uninterrupted by "stuff" in the middle.

Turf and ornamentals have different growing requirements. Lawns require much more fertilizer and water than flowers, trees, shrubs and ground covers do. Ornamental plants require much less mowing than the lawn does, of course. Growing them together compromises one set of plants for the other. If turf and ornamentals are co-mingled, homeowners will tend to water the landscape uniformly, with the end result being the demise of one or the other.

As spring transitions to summer, a lawn needs a transition as well. In April and May, the temperatures are cool, and natural irrigation is normally plentiful-not so in June, July and August. So, in order to give lawns a fighting chance at surviving in 100-degree heat and short periods of drought, raise the mowing height. The higher height of cut creates a taller canopy of turf leaves, which shades the crown of the plant, keeping it cooler. All the new shoots and rhizomes (lateral spreading organs of the turf plant) originate for the turf to continue healthy growth. Shade for the turf from the turf itself. This should be done moderately as drastic mowing height changes allow for a greater surface area, and hence, greater moisture loss. However, allowing a 20 percent or so mowing height increase beneficial as the greater height creates a "canopy effect," and the turf benefits from the increase shading. The benefits are reduced evaporation from the soil surface and direct relationship between taller shoots and deeper roots.

If the customer’s lawn slopes or is heavy clay, it is nearly impossible to apply a week's worth of water with one application. So, instruct them to make three applications of .5 inch to prevent runoff and wasting water.

On flat or relatively flat ground water has a long time to soak in before runoff occurs. As the slope increases, there is a direct increase in runoff potential, causing decreased infiltration.

The result of less water moving downward through the soil profile influences the landscape in two ways-plants at the top of tile slope don't get enough water, and plants at the bottom of the slope get too much. Both results create an unhealthy growing situation for plant roots. Or verly dry roots will slough off, while soggy roots will soon develop root rot.

The outcome of reduced infiltration rate is also influenced by soil type. Every landscape soil has a different infiltration rate. Sandy soils allow water to move through .them rapidly, while those predominant in clay offer great resistance to water infiltration. As you might imagine, a severe slope comprised of a heavy clay soil combines two factors responsible for problem landscape areas.

As discussed earlier in this article, irrigation uniformity is of utmost importance. So, does it make sense to water the top of the slope and not the bottom or the middle? Absolutely. Depending on the degree of slope, water applied to the top will flow downhill, soaking in along the way. In fact, oil a slope, if Neater is applied at the same rate to the top and bottom, the bottom will end up with much more, probably twice as much, as the top. This technique is most effective when used in conjunction with aeration and delayed irrigation starts.

You can prevent a significant part of runoff on a slope by controlling thatch. Thatch is the dead layer of decaying roots, crowns, stolons and sheaths that exists between tile grass blades and the roots. If allowed to build up, it greatly reduces the water infiltration and encourages runoff of applied irrigation water. Reduce thatch through routine aerification and power raking; spring and fall in the North, early summer in the South.