Quick Summary: Start by installing the sprinkler riser on the lateral pipe outlet. Then the sprinkler is screwed onto the riser. Adjust the sprinkler to be in the desired location and perpendicular to the ground surface. Position sprinklers at the edges of the irrigated area about 4″ away from hard surfaces like sidewalks and driveways. If growing a new lawn from seed make provisions to prevent the water spray from the sprinkler from washing the seed away. Details follow!
As soon as the pipes are thoroughly flushed out you’re ready to install the sprinkler heads. When adjacent to sidewalks and curbs the sprinklers should be at least 1″ away from the concrete edge. This allows room for an edger or other tools to operate without hitting the sprinklers. You can install the heads as far as 6″ away from the concrete edge if necessary, although 4″ from paved surfaces is the optimal distance for placement of a sprinkler.
A “riser” is used to connect the sprinkler head to the underground lateral pipe. A good riser allows you to fine tune the location of the sprinkler heads and protects the sprinkler from damage, and it may cost as much or more than the actual sprinkler! Riser types and selection were discussed earlier in the tutorial, see Sprinkler Head Risers or Types of Sprinkler Risers. You will quickly see the advantages of using the swing joint type risers when you begin installing the heads. The swing joints allow you to rotate the heads to just about any position or height.
Sprinkler positioning. In most situations the sprinkler should be positioned so that it is perpendicular to the soil surface. When installing a sprinkler to water a steep slope you may need to lean the sprinkler into (toward) the slope a little to avoid having the water spray straight up into the air. Normally you would come back later and make some adjustments to the sprinkler position on slopes as there are a lot of variables for any specific terrain.
Bending the riser tubes. One word of caution, the flexible poly tube used in the construction of many swing risers has a tendency to want to straighten itself out when bent. As much as possible avoid bending the flexible tube to position the sprinkler. If you bend it the tube will try to go back to it’s original shape over time and may move your sprinkler out of alignment. (Although you can bend the tube if needed, the real purpose of it being flexible is to allow the sprinkler to move when hit by a car or lawn mower.) Try to get the riser worked into a position where the sprinkler stays where you want it by itself. Play around with it a little bit, twisting it this way and that, and you will soon get the hang of it.
Small sprinkler heads (like 2″ & 3″ pop-up models) are harder to keep in position, the short bodies make them less stable and they tend to wobble around a lot. If you have problems keeping them aligned try adding a 2″ to 4″ long sch 80 pvc nipple (gray plastic nipple with male threads both ends) to the bottom inlet of the sprinkler with a pvc threaded ell at the bottom of the nipple. Connect the riser to the ell. This essentially makes the sprinkler body longer, and longer sprinkler bodies tend to be much more stable than short ones. Once you have the sprinkler positioned where you want it, back-fill with soil around the sprinkler head and compact the soil around the sprinkler body. The top of the soil level should be about 1/4″ to 1/2″ below the top of pop-up sprinklers.
Shrub sprinklers on pipes above ground should be avoided where possible. Where they must be used because of tall groundcover plantings, if possible attach them to a large post, so that they are very visible and not a trip hazard. Never use shrub heads sticking up more than 1/2″ above ground near sidewalks, driveways, or other pedestrian paths where they would be a trip hazard. Use a pop-up sprinkler in these locations. You can buy pop-up heads that rise up 6″ or even 12″ above ground when turned on, then retract down into the case underground when finished watering. A pop-up sprinkler is safer than a shrub sprinkler on top of a pipe… and looks a lot better too!
Seeded Lawns and Sprinklers
A common problem is encountered when seeding new lawns with a sprinkler system. When the sprinkler nozzle rises out of the pop-up body the water spray washes away the seed in the area around the sprinkler. Here are three tricks used to deal with this problem.
- The first is to buy a short “riser extension” that screws into the pop-up riser under the nozzle. This raises the nozzle up a few inches higher so it doesn’t wash away the seed. Remove the extensions before the first mowing. Because the extensions can be reused this is a great option for contractors. The riser extensions are hard to find however, and you may have to special order them online or at a irrigation specialty store.
- The second and most common method is to install the sprinkler heads so the top of the sprinklers are 2″ above the ground. The big problem with this method is that you need to dig up the sprinklers and lower them before you mow the lawn for the first time. That’s a lot of work.
- Another method is to cut a hole in the bottom a Styrofoam coffee cup and place it over the top of the sprinkler so that it forms a collar that extends a couple of inches higher than the top of the sprinkler. Stake the cup in place using a couple of wires (the little wire flags used for marking sprinklers work good for this) pushed through the cup into the soil. The cup blocks the water spray while the riser is popping up, but once up, the water sprays over the top of the cup. Remove the cups once the lawn is ready to be mowed the first time.
- The really easy solution for homeowners. Get a heavy rubber band for each sprinkler. Grab the nozzle and pull the riser up out of the case with your fingers. Wrap a rubber band around the riser and push it all the way down the riser until it is against the top of the case. The rubber band will hold the riser up. Before mowing the first time remove the rubber band. Note that this doesn’t work on some “pro” sprinklers that have very strong retraction springs.
A micro-sprinkler, for the purpose of this discussion, is a small spray-type sprinkler that is installed on a 1/4″ diameter poly riser, which is connected to 1/2″ drip irrigation tubing. In many ways they take the disadvantages of a sprinkler system and the disadvantages of a drip system and combine them. They seem like a good idea when seen in a store. But what you don’t see in the store is that they tend to be very high maintenance and have a life-span of only 1 to 2 years. Dogs and wildlife love to chew on them as they have a great texture for chewing. In most cases a regular sprinkler system as described in the rest of this tutorial is going to serve you better over time. You can now buy standard sprinklers made for areas as small as 36 inches wide, the same as a typical micro-sprinkler, so why not use the real thing? Okay with all that said some people do like them and want to use them so a few quick tips.
If you do want to use micro-sprinklers the design process for micro-sprinklers is exactly the same method as for regular sprinklers. Space the sprinklers using head-to-head coverage, calculate GPM/GPH for each sprinkler, create hydro-zones and valve zones, etc. See the sprinkler design tutorial for details. The difference is in the materials and installation. Micro-sprinklers are typically installed on 1/2″ drip tubing laid on the ground surface, just like drip emitters, and the “risers” are 1/4″ tubes that extend to the micro-sprinkler heads.
Drip systems are a great way to water your shrubs. Drip systems are inexpensive, efficient, flexible as to future changes in the landscape, save water and energy compared to sprinklers, and are easy to install. They don’t tend to last as long as underground sprinkler systems in many areas, but the lower cost and installation ease makes up for that. See the separate tutorial, Drip Irrigation Guidelines, for installation of drip systems.
This article is part of the Sprinkler Irrigation Installation Tutorial Series
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