irrigation use

Smart Irrigation Month is Here

The HEAT is definitely on!  Welcome Summertime!

You may have heard by now, that July has been deemed “Smart Irrigation Month” by the Irrigation Association since 2005, because that’s typically when the hottest temperatures occur (here in Central Texas, our hottest months are August and September). With high and hot temperatures come higher water use, it’s just a given. We still want our landscapes to look as good as they have the rest of the year, so we crank up the water.

This year, I’d like to challenge you to do something different. It’s been a slightly different year already: we actually experienced a winter (all Native Texans can appreciate that!!) AND it was a wonderful spring—again, that’s amazing since we usually go from winter straight to summer!  We didn’t have a 100-degree day until this last week and really haven’t needed to use the irrigation system until June.

In honor of Smart Irrigation Month, I’m going to ask you to something different by investing in your irrigation system and upgrade where necessary.  Don’t just turn it on and forget it all summer.  I want to focus on sprinkler heads and water pressure. The type of sprinkler head being used determines several things, like how long to water, where to locate the heads, and also how much water is being emitted and, most importantly, how well that water is being used by your landscape.

There are two main types of sprinkler heads—spray heads and rotor (or rotary) heads. Both are usually buried underground and pop-up when watering. Spray heads spray water the same piece of grass, or landscaping, the entire time they are popped up. Rotor heads turn to the left, right, or in a circle, when they pop-up and do not water the same place the entire time they are popped up.  They can have one large stream of water spraying out or smaller streams of water spraying.  With either pattern, they turn, versus being stationary. See the pictures on the right for what each look like.

Rotor heads are the more efficient of the two head types. Tests have shown that the water is distributed more evenly by rotor heads than spray heads. The same amount of water is being emitted close to the head as midway as at the furthest end of the water. Usually people want to replace rotors with sprays, but I urge them not to. Again, they are more efficient than traditional spray heads. Rotor heads are desirable to use in large areas—fewer heads are required to cover a large space since they spray water out a further distance than spray heads.

Traditional spray heads are not quite as efficient, mainly due to variations in water pressure and head spacing (specifically heads placed too far apart). Misting is commonly seen with spray heads—this is lots of “clouding” coming off the heads. This cloud, or misting, is water drops that are so small they are just floating away into the air, rather than going down onto the landscape. You are paying for this water and it’s just floating away. Not good. This means you have to run the system for a longer time to get water down onto the ground, which will get expensive and is just wasteful. This is caused by water pressure that is too high.

An aside here, “good” or appropriate water pressure for irrigation systems is between 35-60 psi.

High pressure can be remedied in two main ways: installing a pressure reducing valve (PRV) on the irrigation system, or replacing the nozzles with ones that adjust or compensate for the high water pressure. So…which is better? That’s a hard question to give a quick answer for.

The PRV is a good fix if the entire irrigation system is running with high pressure. It’s one device that is installed near the backflow prevention device in your yard. A licensed irrigator should be contacted to install this device.

Replacing nozzles is a great way to fine-tune the irrigation system; here, you can just replace nozzles in the zones that have the high misting. This is a little more time consuming because you need to find and purchase the correct nozzle types (full circle, half circle, etc) and then physically unscrew the old nozzles and screw on the new ones, but overall it’s pretty inexpensive. Of course, a licensed irrigator can be hired to do this work as well. There are several brands of nozzles that have built-in pressure compensation and can be ordered online or found in local irrigation stores.

Both types of pressure reducing qualify for the City’s Efficient Irrigation Rebate program. I highly encourage you to take advantage of it if you notice misting in your irrigation system!

Water Less this Fall

Now that we’re officially into Fall hill-country-highlights-watching-the-leaves-change-at-lost-maples-state-parkand enjoying some cooler temperatures; it’s time to reduce the watering times on your irrigation controllers.  With less evaporation occurring, the landscape doesn’t need to be watered as often as during the summer months.  My general rule of thumb is: cut watering times in half during Fall and Spring

If you don’t really know how much you should be watering to begin with, let me go over the 3 basic things to look at to determine how long the system should be running because, there’s no point in having specialized heads, a shady yard, and native plants if everything is going to run for 20 minutes no matter what it is.  Unfortunately, I see that happen a lot.

Amount of Light

It may seem obvious, but I’m going to come out and say it anyway—shady areas require less water than sunny areas.  If you have good tree coverage and areas of the yard receive less than 6 hours of direct sunlight daily, that’s considered a shady yard.  So, when entering time into your controller, you know that the times should be higher for the sunny spots and lower for the shady ones.

Head Type

There are two main sprinkler head typesrotor and spray.  There is also drip irrigation, which technically has no head at all!

  • Rotor heads rotate, they turn, so they are not watering the same area the entire time they are running, therefore, they need to run for a longer period of time than spray heads.
  • Spray heads are stationary, they pop-up and stay watering the same spot the entire time; they can run for a shorter amount of time than rotors.
  • Drip irrigation is different. Drip typically emits water very slowly, very minimally, so it oftentimes needs to run for longer periods—30 minutes at minimum or much longer in many cases.

Plant Material

Landscape (read: living plant) material is the last component of the irrigation scheduling trifecta.  It may be obvious as well, but it does need to be said—areas with no vegetation really don’t need to be watered.  The bare ground will just be muddy.  Same goes for rocky paths, they don’t grow.  Mulched areas don’t grow.  Driveways, sidewalks, patios, and decks don’t grow.  Pools don’t need to be filled by the sprinklers.

Native plants, established shrubs, or other established perennials do not, I repeat, do not need the same amount of water as the grass.  That’s why you’ve planted them—they are native and require less water to survive.  They are made for our climate and weather conditions.   So, turn those stations off completely in the fall, winter, and spring and just water when they look stressed (i.e. droopy leaves, limbs first thing in the morning).

You may have picked up that there’s no exact time that works for every station or even every yard!  Irrigation systems unfortunately aren’t just a turn it on and forget it.  It will take a little tweaking to determine how few minutes the yard will perform well on, and it may need to be changed every year as the trees grow and give out more shade.

Here’s a watering schedule I follow, when irrigation is necessary during the Fall months:

Fall—October, maybe November

Set controllers for 1 start time for all lawn types.

Plant

Exposure

Type of Sprinkler Head

How Often to Water

Runtime (minutes)

St. Augustinesunsprayas needed, max. 1x/wk10 to 15
  rotoras needed, max. 1x/wk15 to 20
 shadesprayrarely, 1x per 2 wks15
  rotorrarely, 1x per 2 wks20
Bermudagrasssunsprayrarely, 1x per 2 wks15
  rotorrarely, 1x per 2 wks20
 shadesprayrarely, 1x per 2 wks10
  rotorrarely, 1x per 2 wks20
Zoysia japonica (wide blade zoysia, El Toro, JaMur, Palisades)sunsprayas needed, max. 1x/wk10 to 15
  rotoras needed, max. 1x/wk20
 shadesprayrarely, 1x per 2 wks15
  rotorrarely, 1x per 2 wks20
Common shrubssunsprayrarely, 1x per 2 wks10 to 15
  rotorrarely, 1x per 2 wks20
 shadesprayrarely, 1x per 2 wks15
  rotorrarely, 1x per 2 wks20
Common groundcoverssunsprayrarely, 1x per 2 wks10-15
  rotorrarely, 1x per 2 wks20
 shadesprayrarely, 1x per 2 wks15
  rotorrarely, 1x per 2 wks20