February 8, 2013

Irrigation or Irritation System ?

When do you need just a "sprinkler" and when does the need morph into an "irrigation system" ? Part 1- the irrigation heads. 

At some point in most gardens, you will need a sprinkler device to water an area or to water in newly planted trees or a landscape section. This begins a cycle that I call the Irrigation Ladder. This cycle is much like the Automobile Ladder or Real Estate Ladder or even the Corporate ladder, wherein you start small and work up to increasingly complex levels, along with a greater risk / reward profile. There are hundreds of choices of irrigation heads, and technology improves them every few years. One of the most recent developments has been the stream-rotor head, combining the best of rotor and spray-head technology into one, very efficient and fairly trouble-free device. Suitable for mixed-planting and turf areas including flower beds, this new type of head can be very effective, although rather expensive to install.  
stream-rotor pop-up head
photo courtesy of Popular Mechanics 

A stand-alone sprinkler is a wonderful device, so simple, so easy to use, no frustration or installation issues; just plug it into a hose and turn on the water. Many property owners decide to have a permanent irrigation system installed, also called an in-ground or solid-set irrigation system with an electronic timer. Things can get complicated when you do this, but there are ways to streamline the project a bit and de-complicate the process. One of the first things to consider is whether you need a whole system or just a sprinkler or two.  Learning a bit about how sprinkler heads apply water can assist with the decision of which one to buy.As a general rule, there are 2 types of sprinklers: those for occasional use, connected to a hose and operated manually by opening a hose tap, and those which are permanently installed onto piping and operated automatically by a controller.

There are several basic groups of sprinklers ( when they get expensive, then we call them irrigation heads ), so I'll list a few of them for easy reference.
One of the most common sprinkler types is still one of the most effective, but not necessarily the most efficient. Some call this kind of sprinkler a "rainbow"; since it often produces rainbows in the mist of the water streams. This is a great device for occasional watering, they are inexpensive and it can water a surprisingly large area, and can soak lawn grass very quickly. It is not very useful for deep-soaking trees or for watering landscape beds or densely planted areas; the water streams can be easily diverted by branches or dense foliage.The sprinklers shown here are can be operated either manually or automatically, but a rainbow sprinkler needs to be above ground to work well.   

Rainbow sprinkler

Another very common type of sprinkler is the pop-up spray head, termed as such because the central stem of the device pop ups from the casing, and "pops down" when the water is off, leaving a smooth contour at ground level so that the sprinkler is not damaged by lawn mowers or foot traffic.This type of device can produce a lot of water quickly, but is still more suited for open areas rather than dense plantings. There are numerous variants for spray heads regarding the fractions of a circle of coverage. The area covered is less than a rainbow sprinkler, but the heads are less visible, cost less, and are more uniform in water coverage than a rainbow type. The heads need to be spaced close enough to allow the spray from one head to overlap the spray from another head. This design calls for numerous heads connected by underground piping or by a hose. This type of head is excellent for flower beds or areas where a lot of water is needed but there isn't much to block the spray pattern.

pop-up spray head
photo courtesy of Green's Lawn Service

One of the more recent types of sprinkler heads is called a rotor head, and it emits water in a long stream which rotates from the head in a circular pattern, usually taking 1-3 minutes to complete a circle. These heads are excellent for covering large open areas, and can even be used in dense plantings or where many trunks can obstruct the water stream path. These heads require high water volume and good water pressure to work best, and are ideal for large lawns or golf courses. They are not very suitable for small  or complicated mixed-plant landscapes where smaller irrigation heads would do the job better. This is one of the most efficient sprinkler types, but is one of the slowest to apply water. A rotor head will take over an hour to apply one irrigation-inch of water, where a spray head would take 15-20 minutes. This type of sprinkler is not really suitable for tree root-zone soaking or deep irrigation, nor for flower beds where the strong water stream would damage flowers. 

rotor head
  With all these options and an endless array of options of design, how can you choose which sprinkler head is best for you ? The answer is to match the right sprinkler head to the right landscape area: spray heads for flower beds, rotor heads for large open areas,and a stream-rotor head to cover areas with turf and landscape plants mixed in. Consulting a landscape irrigation professional will help in designing systems to suit your landscape needs. University Agriculture Extension Service agents can be of great help in designing a water-efficient system to suit your budget and save water at the same time. Keep in mind that many states have watering restrictions, and some states actually specify which irrigation heads can be used in residential landscapes. Designing a good irrigation system is easier than you think, and even a rainbow sprinkler can be effective when used in accordance with its abilities. Many plants will actually grow better with less water than people think is needed, especially in winter months or in rainy periods. Water is one of our most valuable resources, we should all strive to conserve it, one home at a time. 

Craig Morell
Pinecrest Gardens