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Irrigation Tips


One of the worst things you can do for your turf is to over-water, which discourages the development a deep root system. Think back to spring and summer of 2010…a season with a cold, wet spring; Mother Nature, on her own, caused our turf to have a shallow (and lazy!) root system. Then we had a warm, wet summer…yet many of you continued to water the lawn because you “thought” you had to…thus, extending the period of poor root growth. Along came some dreadful and prolonged heat in August, with very hot nights (lows is the 80’s). That’s when most turf just went “belly up.” It simply “cooked.” The summer of 2010 was the “perfect storm” for our turfgrass woes. There’s nothing we could have done about the cold wet spring, or the hot August, or the regular, heavy rainfalls through the summer. The only thing in our control is how we managed our irrigation, and our fertilizers.Irrigation Minutia

When we go through periods of abundant natural rainfalls, you’ve got to exercise a modicum of common sense and turn your irrigation system off! We’ve got to let the roots do their job! The rainfalls in the summer of 2010 were characterized as numerous and soaking! Those rains were sufficient to supply the turf for 3 to 4 days! Still, many of you folks kept the irrigation system running on your “every-other-day-cycles!” Wrong, wrong, WRONG! You have to encourage your turf to develop deep roots–work with Mother Nature. That was a season where watering more than once per week was too much, much less 3 to 4 times per week. The “tough turf” year of 2010 serves as a reminder to all of you “irrigators” that a shallow root system will dramatically increase the likelihood of dead turf in August.

If you really aspire for great turf, take a few minutes and walk your property in the evening. If the soil surface is moist to the touch then turn the irrigation clock to “off.” Remember, turf ain’t moss.

We’ve had a lot of questions about watering, such as “Must I water?”, “When should I water?” and “How much should I water?” Here are our opinions and experience on this subject. But you need to know that these are just guidelines because every zone in your yard requires some customization of the settings…whether that be the minutes per zone, or the nozzle size in that particular irrigation head.

Must I Water?

No, you don’t need to water your turf, because it can survive without additional irrigation…well, maybe 9 years out of 10. But, if you aspire for fabulous turf, you should (must) irrigate. If Mother Nature decides to ignore us, your turf will go dormant on its own, and commence growth again in the fall, when the temperatures cool down and fall rains return. However, most of us “burbanites” want a green sward, and/or we can’t tolerate the peer pressure of high neighborhood standards, thus we irrigate. Once you start providing supplement irrigation (during late spring) you really can’t stop, because the sudden withholding of water prevents it from slowly sliding into dormancy. So, if the quarterly water bill comes in too high for your budget you can’t stop watering all of a sudden. If you’re managing your household budget tightly in our poor economy, perhaps you shouldn’t irrigate the sward…it’s OK…not irrigating at all is probably better than stopping abruptly in July or August.

When Should I Water?

Hands down, the best time of day to water is in the early morning. For those of us with an irrigation system, program the clock to start at 4:00 to 5:00 A.M. In general, water every second to every third morning. It’s hard to tell you how much to apply, but try to water sufficiently long to get the top inch or two of soil moist. Remember, gravity sucks! That means the moisture in the surface soil will work its way deeper into the soil profile. Let the soil surface dry between your water cycles (remember the comment to walk your property in the evening?). The most accurate advice we can give you requires you to make a decision most evenings at dusk…if the soil surface is damp, don’t water the next day. All you have to do is turn the timer clock to the “off position”. Don’t be a mondo-dope, though, and forget the turn the clock back on! A good buddy of Jeff’s did this, and caught holy-hell from his gal! No need to give those women more ammo.

Watering in the late evening will typically make diseases worse because the turf stays wet through the night. Fungal diseases require a film of water on leaf surfaces to grow and spread their mycelia. Watering late in the day (typically after 5 PM) keeps the turf wet through the night, so just don’t do it. Those fun-guys (get it?) will party at your expense! Brown patch, the biggest nasty of all our diseases of fescues, is far worse when the turf stays wet through the night, from either late watering or from the dews associated with high humidity.

There may be times when you have to water in the middle of the afternoon or the evening, when your turf is under severe water stress. Should this be the case don’t get all freaky–just do it and relax. How can you tell your turf is under severe drought stress? Well, it takes on a bluish-gray tint, because of the way the leaves roll slightly in their attempt to minimize water loss. Probably the best of all indicators is that you’ll see your own footprints in a droughty lawn. Just don’t make a practice of watering after 5 PM.

If you don’t have an irrigation system, get yourself a nice digital timer, plus a half-dozen new hose washers. Now you’re asking, “Why hose washers?” Well, if you’re going to use a digital timer you’ve got to leave your faucet in the “on” position for extended periods of time. If your washers are old, your hoses are prone to leaking through the bad couplings. Set the hose and sprinkler up in the evening, and program the timer to come on at 4:00 AM and off at 5:00 AM. After your morning coffee, before you head to work, reset the sprinkler position and the timer, and get another “zone” watered while you’re at work. You can rotate a good sprinkler through a typical yard several times in a week with this method. And you no longer have to whine about not having the $4K for a decent irrigation system!

Let’s do a Dew Wash!

Watering very lightly, 2 to 3 minutes per zone at daybreak works well to minimize disease pressure, because disease spores can be knocked down off the leaf surface into the thatch, thus slowing (but not preventing) the spread of diseases. Plus, “water of guttation”, that drop of sugary water that is exuded out the cut surface of the leaf tip, sitting atop the leaf blade, serves as a literal nutrient broth for disease spores. This is an early morning phenomenon, and thus, a very brief irrigation will “wash” the sugar solution away, further hindering the spread of diseases. In the dog days of summer, program each zone to come on for 2 to 3 minutes in the morning, starting at 4:00 AM. We call this a “dew wash!”

How Much Should I Water?

That’s a good question. The answer? It depends. And it also depends if we’re talking about established turf or newly seeded turf. It depends if we’re talking about a zone that’s in full sun, partial shade, or full shade. Is the soil flat or is it sloped?

To support newly seeded turf you need to make frequent, shallow irrigations, when the turf is developing, and maybe even twice a day if the soil is really dry and the temps are above 90F! A seedling has a poorly developed root system and hence, benefits from frequent irrigation. As it grows and develops start watering more deeply and less frequently. It’s so damned annoying when we hear or read garden columnists and so-called experts tell us…”Water deeply so that your soil is moist at a depth of 6 inches.” Who are they kidding? The tight clay soils of St. Louis would be pure slop on the surface if we could get wet our soils to 6 inches. Plus, our clay soils have a percolation rate (the rate at which they’ll take water) of a meager 1/16th inch per hour. So do the math! In actuality, we have to resort to frequent watering to keep our clay soils moist.

Most everyone, including the garden columnists and radio talk show hosts, agree that turf requires a minimum of an inch of water per week. If it’s hot and dry and we don’t get rain, you have to supply that inch. If we catch a half-inch rain, you only have to supply the missing half-inch. We think this rule is a good guideline but you’ll have to customize it to your specific situation. For example, one zone in Jeff’s back yard is a west-facing slope, which gets blistered by hot afternoon sun. That zone gets watered daily, while the rest of the yard gets water 3 times each week. With an inch of water per week your lawn may not look like the fairways at Bellerieve Country Club, but it’ll be very healthy and green. Most fabulous lawns are watered at least every other day during hot and dry weather.

Changing Tips On Spray Heads

Don’t just assume each zone needs the same “time” or amount. It’s very common for your irrigation company to simply program every zone for 15 to 20 minutes of water, every other day. When you have an irrigation system installed, that’s what the company typically sets up for you…their “default setting”. Depending upon the exposure to sun or shade, sloped vs. flat ground, etc., those zones may not necessarily need 20 minutes of water. The shady side of the house will be sloppy wet, compared to the zones in full sun, if watered the same way. To double-check your settings, walk each zone immediately after it turns off. If you have water draining away from that zone, you’re wasting it. Either reduce the duration of that zone (minutes in the “on” position), or reduce the actual nozzle size in the sprinkler head. If the turf still looks stressed in the heat of the day, or you can see definite footprints, increase the time on that zone.

In each of those irrigation heads is a small, plastic orifice, called a “nozzle” or a “tip”, which controls how much water shoots through the head. The sprinkler head has different-sized nozzles, and they aren’t hard to change, but you need a special tool, that’s specific to the brand of heads you’ve got. Your irrigation provider should have provided you with the tool, along with several dozen extra nozzles. AND they should have spent a few minutes showing you how to make the changes! It may take you a month or two to “fine tune” each zone on your irrigation system, but it’s important fine that “sweet spot” for each zone in your system. Many of you don’t realize how easy this is to do.

If this stuff is new to you, have your irrigation contractor come out and explain it to you, and get an assortment of nozzles from them. They should have shown you how to adjust the spray pattern and set the clock, etc. If they didn’t, call a different company. The best guy in the business is Tim Radcliffe, from Horstmann Brothers. Call him at 314-574-1928. Be sure to tell him we sent you!

System Overrides

Come on folks. Nothing looks as stupid to everyone else in the neighborhood as having your irrigation system running during in the middle of a thunderstorm! And just as bad, the morning after a heavy rain. How can you invest a couple of grand into an irrigation system and not get a rainfall over-ride switch? An over-ride is an automatic shut-off switch. There are various designs available, and they cost $150 to $250. They are worth every cent.

Final Words

It’s hard to communicate all the tricks of the trade over what would appear to be an easy turf topic (watering). It’s not rocket science, but a beautiful turf sward in August darn near requires as much schooling!

(Note: This blog was originally posted on April 10, 2012.)