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 you like. You will quickly see the advantages of using the flexible swing joint risers when you begin installing the heads. The flexible swing joints allow you to rotate the heads to just about any position. One word of caution, the flexible pipe has a tendency to want to straighten itself out when bent. As much as possible avoid bending the pipe. (Although you can bend the pipe if needed, the real purpose of it being flexible is to allow the sprinkler to move rather than break 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 without being supported, or at least with the least amount of support possible. Play around with it a little bit, twisting it this way and that, and you will soon get the hang of it. If the sprinkler heads keep bending over at an angle or wobble a lot try adding a 4" to 6" length of pipe to the bottom inlet of the sprinkler with a TxT ELL at the bottom of the pipe. 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. Next back-fill around the sprinkler head and compact the dirt around the sprinkler body. 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 make them tall, and if possible attach them to a large post, so that they are very visible and not a trip hazard. Never use shrub heads near sidewalks, driveways, or other pedestrian paths.
A common problem is encountered when seeding new lawns with a new sprinkler system. When the sprinkler nozzle rises out of the body the water spray washes away the seed in the area around the sprinkler. Here are three tricks used to reduce 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 may be a special order item at a lot of stores.
- 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 and I'm too lazy for that! So forget this one.
- An alternate 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.
For surface installed drip systems snake the tubing between the plants to be watered taking care that the total length of the tube doesn't exceed the maximum allowable length recommended by the emitter manufacturer. Stake the tubing to the ground every 3 feet. You can purchase stakes for holding down the tubing, but I recommend that you make your own, I find the manufactured ones don't work very well, particularly the plastic ones. The best stakes are made from plain steel wire, do not use galvanized or stainless steel. You want the steel to rust. The rust is what binds the steel stake to the ground so that it doesn't pull out. There are two products I know of that work well. The first is erosion control staples. These are heavy 6" inch long wire staples that are used to staple down erosion control blankets and weed barrier fabric to the soil. They are not always easy to find, sometimes they are sold along with the weed barrier fabrics at garden centers. Also try landscape specialty irrigation stores, many also sell erosion control products. The other product that works well are the wire sprinkler staking flags that most irrigation stores sell in bundles of 100. Each flag consists of a 12" to 18" long spring-steel wire with a bright colored plastic flag on one end. Rip off the flag and cut the wire in half. Bend one end of the wire over into a hook (like a shepherd's hook) and you have a very effective stake. After a few years these stakes will completely rust away, but by that time the tubing will have settled and will stay in place. If you do not stake the tubing down it will move around as it expands during day and shrinks at night and the emitters may be moved away from the plants. The stakes also hold the tubing down tight to the ground which looks a lot better.
It is best not to bury the drip tube unless you are absolutely sure that you currently don't have, and never will have, gophers or moles. They both love to chew on the buried tubing (I have no idea why. Maybe they want the water.) In some areas squirrels will chew on the tube if it is above ground. If you have both squirrels and gophers you're doomed! (Well maybe. Some people have found the squirrels leave the tube alone if you provide them with another source of water to drink.) An alternative to burying the tubing that works well is to make a shallow trench about 2" deep and stake the tube in the trench but don't cover it with dirt. Then spread a layer of bark or rock over the entire planter including the open trenches. Never bury the emitters unless they are designed to be buried and the manufacturer offers a long-term warranty that covers root intrusion. Most emitters that are made to be buried use a chemical herbicide to prevent roots from growing into them. University research indicates that buried emitters without a chemical root barrier become plugged by roots within a few years. If you do decide to bury the tubing it is typical to bury it between 4-6" deep. If watering trees I have on occasion buried the tubing as much as 12" deep, but for many smaller plants that depth places the emitters below much of the root system, especially when the shrubs are young. Polyethylene pipe which is buried 6" deep or less has a nasty habit of surfacing during the winter. What happens is that the tube fills with air when not being used, and then the winter rain saturates the soil with water. The air in the tube combined with expanding and contracting of the tube results in the tube floating to the soil surface! So you will still need to stake the tube every 5' or so even if it is buried!
Most emitters have a small barb that you snap into a hole punched into the tube. These are called snap-on, or button, emitters. Be careful when punching the hole that you do not punch all the way through the other side of the pipe. Have some goof plugs handy to plug the holes just in case! Another type of emitter, referred to as in-line style, are installed by cutting the tube and inserting the emitter into it. In most cases the in-line style emitters come pre-installed in the tube at a set spacing between emitters. Some are molded directly into the tubing during manufacturing. This type of emitter tube saves you the work of installing the emitters on the tube. In a lot of ways this is really a better system, most people have a tendency not to install enough emitters, and the installation is a lot easier. After installing the emitters it is very important that you open the end of the tube and run the water to flush out any little pieces of plastic left over from punching the holes or manufacturing.
Do not place emitters directly at the stem of the plant. For newly planted shrubs and trees the first emitter should be over the root-ball, but as far as possible from the stem. For established plants the emitter should be at least a foot away from the stem or trunk. The next emitter should be no less than 24 inches away from the first! Remember that a single emitter will saturate the soil with water in at least a 36" diameter area around the emitter in sandy soil, and an even larger area in clay soil. There is no point in adding more water in this area, the soil is already saturated! So space the emitters at least 2 feet apart. (Exception: for lawns you should use in-line emitters spaced a foot apart, with the emitter tubes in rows 18" apart.) Always use at least two emitters for each shrub. That way if one emitter becomes plugged you will have a back-up emitter to keep the shrub alive. Most trees need 5 or more emitters. As a rule of thumb the area wetted by the emitters should be equal to the area shaded by the plant's foliage at noon.
I have an extreme dislike of "spaghetti" tubing (proper name: distribution tube) and it's companion product, multi-outlet emitters. The small tubing just doesn't hold up in the commercial landscape situations I deal with, and I wouldn't even use it in residential landscapes. For our purposes here I'm going to suggest that you should not use tubing smaller than 1/2" diameter. The smaller tubes are just too easily damaged. If even an animal as small as a cat kicks one of these tiny tubes it will move the tube. I've found that in order to keep the tiny tubes in place they have to be staked to the ground once for every foot of length. What a pain in the rear! Just run the larger tube everywhere and forget this small stuff. You will not regret it.
As usual I will now backtrack a little and say there is a situation where I do use distribution tube. Sometimes I will install a temporary length of distribution tube to the root-ball of a newly planted shrub or tree to make sure it gets water. This way I don't have to install an emitter close to the plant stem that might need to be relocated later. After the plant is established I remove the distribution tube.
I've never been too excited about micro-sprinklers. Seems to me they are a combination of the disadvantages of sprinklers and the disadvantages of drip systems combined into one. The only non-agricultural (they're great in orchards) situation where I can imagine using them would be an annual flower bed. But in a flower bed I would want them installed on PVC pipe because I know the poly tube would be damaged by the seasonal replacement of the flowers. So why not just use a regular sprinkler system since it would be less expensive? Others, however, disagree and say I'm all wet. So... I'll dry off and give you a little information on the design and installation of 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 installation. Micro-sprinklers can be installed on PVC laterals like regular sprinklers (because you will have lots of sprinklers very close together this can be very expensive!) or they can be installed on drip tubing just like emitters. That's about it. Good luck.
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