Sprinkler System Nozzles for Best Plant Health
Current research shows that homeowners can save 50-70% of their water bill by setting up the sprinkler system for optimal water use and using native plants in landscaping. Plants are healthier too.
Watering too much hurts plants as much or more than watering too little, and most people do water too much. It robs the soil of air, which plant roots need, by flooding out the little worm tunnels and spaces between different sized soil bits.
What's more, any water you use in excess of what's actually needed, or that runs off the surface of your lawn into the storm drains, is water you have thrown away. You waste money by paying for water you don't need or use. This article will show you the best kinds of sprinkler nozzles to use for the types of plants you have.
Flooding Kills Microbes & Hurts Plants
The majority of growth activity that goes on with a plant is underground. In addition to worms and small bugs, there are microbes under the ground that help transform soil into nutrients for plants. All of these organisms need air to breathe.
Air seeps in through wormholes and other little pockets in the soil. The more tightly compacted the soil is (like clay) or the more waterlogged it is, the less oxygen there is available for these organisms to breathe and do their work. It's important to water enough to wet the soil thoroughly, but then leave time for the water to sink in and be replaced by air, before watering again.
Utilizing the Water You Pay For
To save water in landscaping, there are three main areas to pay attention to: The types of plants you use, the type of irrigation controller you install and how it's programmed, and the types of nozzles you use. These all need to be set up wisely in coordination with each other in order to maximize your water use.
The types of plants you use should be those that thrive naturally in your local environment or hybrids of those. The natural, local plant survivors have evolved with local soils, weather, and supporting insect life. When planted appropriately, they do not need much care.
A good irrigation controller is programmed to supplement the natural rainfall, rather than change it to create some other kind of climate (which will hurt the bugs that support the plants). The controller will have a way of measuring soil or air moisture, or the amount of sunlight, or recent and upcoming natural weather patterns. And the nozzles that are right for your landscape will be those that feed water to your plants in the way that they need it.
Irrigation System Nozzles
There are three main types of nozzles, with sub-types within them: Popup or rotor spray nozzles, bubbler heads, and drip/soaker systems. Each works best for a different type of planting. For lawns, spray works best because of the even application. For trees and shrubs, bubblers work best because of the pooling effect. For crops and some flower beds, drip and soaker hoses work best because of the direct application to the plant base. Each type is explained below in more detail.
Spray Heads and Rotors
What characterizes spray heads (and rotors) is that they spray water up and outward in an even application. This applies water to the surface of plants, including leaves. Since many types of plants do not like their leaves watered, this type of sprinkler is best suited for grass, but not flower beds.
This rotary nozzle is specially built to spray out large water drops that fall to the ground, instead of evaporating or being blown away by the wind.
Although there are sprinklers that stand high even when inactive, most irrigation systems are equipped with nozzles that rest in the ground and only pop up when activated by the controller. They are used in locations where a lawnmower is likely to damage anything standing higher than grass level. Popup spray heads are used for small lawns and popup rotors are used for large lawns.
Spray heads come in different sizes and spray patterns. There are some that spray steadily in a 360 degree circle, which are used in the middle of a lawn. There are some that spray in a 180 degree arc, i.e. out of only one side, used on the sides of lawns with the spray pointing inward. There are some that spray in only a quarter of a circle (90 degree arc), which are used on corners. And there are 60 degree nozzles that are used for really tight corners. It is important with the smaller types to make sure that they are spraying in the right direction, so you don't waste water spraying a sidewalk or driveway ("arc misalignment").
In California many of the soils have heavy clay content, which makes them absorb water slowly. The standard spray nozzle gives out too much water for these types of soils. It pumps water constantly, not giving it time to soak in, so water very quickly starts to run off the top of the soil into the storm drains. That is wasted water. It also pumps water up into the air, which allows for easy evaporation by the sun and for any wind to carry it off. That also is wasted water. The newest nozzles make allowances for both of these situations.
The newest types of spray nozzles on the market today that water suppliers are paying the most attention to (and giving rebates for) are the rotary stream (or multi-stream) nozzle and the precision nozzle.
The spray of a rotary stream nozzle looks like fingers of water spraying out, rotating slowly from side to side to cover an area, giving time for the water to soak down into the soil.
The precision nozzle is built so the water slows down and becomes slightly heavier before spraying out. This cuts down on evaporation and wind-blow, saving the 30% of water that would otherwise be lost. The rotating nozzle is well used for heavy soils, the precision nozzle where wind and/or sun are strong.
Rotors are sprayers with a very narrow outlet that emit water under high pressure, sending it in jets out 18-55 feet, depending on the size. Rotors rotate back and forth to give soil plenty of time to absorb the water before its rotation brings the jet back.
Most rotors are driven by gears and come in kits with several sizes of nozzles. They need a higher water pressure than spray heads to operate properly. Whereas spray heads need 20-30 psi (pressure per square inch), rotors vary depending on how far you want them to shoot. If you are watering a 30 foot length, you'll need at least 30 psi coming through the pipes. If a 55 foot length, you'll need at least 55 psi.
Bubblers are nozzles that bubble over in place, rather than spraying outward to cover a wide area. Bubbler nozzles are placed near the base of shrubs or trees to soak the ground around them. In an area where the irrigation system was installed before planting, shrubs and trees should be planted near a riser to which bubbler heads can be affixed.
Bubblers emit water at a slower speed than sprayers do and can be left to run longer. The intention is to create a pooling of water that sinks down deep into the soil around the shrub or tree, then leave a long time of not watering, so that roots have to search for it, growing deeper as the soil dries on top. Bubbler systems are not regulated by water suppliers, hence can be run at the hour and length of time that is optimal for the shrub.
Drip Nozzles and Soaker Hoses
Drip and soaker systems are characterized by long hoses that stretch the length of a flower bed or crop row, or that wind around inside of the bed. These systems almost "leak" water, compared to spray heads. They require a long time of watering to produce the amount desired, but also make it easy for the water to absorb into the soil.
Because there is no runoff and no problem with evaporation or wind-blow, a tremendous amount of water is saved. Drip and soaker systems are a little more vulnerable to blockage than are spray heads, but careful maintenance will make their utilization worthwhile.
In addition, plants are healthier because of the lack of water on their leaves. It is desirable to water leaves on occasion, just to remove dust and insect debris, but water left on leaves in the hot sun can cause them to "boil," and water left on leaves for long periods of time, especially at night, can cause the leaves to rot.
Drip systems have mini-hoses extending from the main hose that are capped by an emitter. Each mini-hose is directed toward the base of a plant, where they dribble water until the ground around it is soaked. For irrigation systems already set up to use spray heads, there are drip nozzles that look like octopus arms that can replace the spray head. Each arm can be pointed in a different direction.
A soaker hose is made of canvas to allow water to leak through the surface, or of plastic with tiny holes spaced regularly down its length. Using a soaker hose down a row of crops allows for the roots to be watered without watering the surrounding soil, which also helps to minimize the growth of weeds between rows.
Water-Saving Rebates and Incentives
As with any water-saving device, check with your local water district before purchasing anything, to see if they offer incentives. Some will give free nozzles, some will offer rebates, some will send a representative to help with planning. Northern California's East Bay Municipal Utility District (EBMUD) offers rebates that will cover a high percentage of irrigation retrofit costs.
Notes & Cautions:
- Note that system types can be mixed in a landscape, as long as each type is linked to a different irrigation station. The stations allow for different watering schedules.
- Also note that when you landscape with native plants they won't need much, if any, water at all. Many water suppliers offer contests or rebates for changing lawns to native plants.
- Whatever system or combination of systems you end up using, if watering is appropriate to the plant type and the local weather patterns, you will end up with healthy plants and substantially reduced water bills.
- Of course, it's important to check for leaks regularly and get them fixed as well.
For more water savings:
- How to Practice Water Conservation
One of the threats most common to much of the world is the drying up of water. Without water we cannot live. Here are ways individuals can use water efficiently, so there is enough for everyone.
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