Figure 1. Rotary impact sprinkler for hose-end use.

Even though it seems to rain a lot in Louisiana, we still need to water our lawns and gardens during some parts of the year.
 
Drip irrigation and permanently installed sprinkler systems are wonderful, but not everybody has access to them. In many cases, a hose-end sprinkler must be used. There are many choices available.

Rotary Impact Sprinklers
Rotary impact sprinklers(Figure 1) were developed for agriculture and commercial turf use but are now common on hose-end homeowner sprinklers. They use a water-driven flapper that hits an anvil and thus incrementally drives the nozzles in a circular pattern. There are two nozzles: one sprays further out while the other covers the area in close to the sprinkler at the center of the pattern. On many models, it is possible to set the sprinkler for a partial circle; the sprinkler will then reverse to the starting point and water the same arc again. Diameter of the circle depends on sprinkler design and water pressure.
 
There may be other adjustments such as vertical angle of the nozzle(s). These sprinklers cover a circle or arc. Because the pattern is not uniform from the center to the extremities, a single sprinkler setting will not give a uniform pattern. Using multiple sprinklers (or multiple sets with one sprinkler) and overlapping so that the edge of the pattern from one sprinkler or set reaches the centers of the adjacent sprinklers or sets, it is possible to achieve a reasonably uniform pattern.

Oscillating Sprinklers
Oscillating sprinklers (Figure 2) were popular in the past but have been somewhat replaced in popularity by rotary impact sprinklers. Even under the best of circumstances, oscillating sprinklers have a poor pattern. At first glance,

Figure 2. Oscillating sprinkler for hose-end use.

the pattern looks good because it is roughly square and it is easier to match up square patterns for overall coverage than round patterns.
 
The problem is that the water delivery rate at the opposite sides of the oscillating sprinkler pattern tends to be much heavier than the rate at the center, an undesirable situation. A square pattern should be either uniform throughout so that patterns can be abutted, or taper from the middle out to allow overlap, as with rotary impact sprinklers.
 
Many oscillating sprinklers offer adjustments that allow one-sided operation or narrow operation. These do not improve the pattern situation.

Traveling Sprinklers
Sprinklers that travel along the hose are useful for watering a larger area. These sprinklers are not popular today, but many are still around. Because they constantly move and change the overlapped pattern, they may provide more uniform overall coverage.

Specialized Sprinklers
There are many versions of specialized sprinklers. Some do an excellent job, and some are gimmicks. One version that works well is a small sprinkler that puts out a square pattern. The square pattern from this sprinkler (Figu

Figure 3. Sprinkler to deliver square pattern.

re 3) is much more uniform than from an oscillating sprinkler. By turning down the water volume, you can control the size of the square pattern, thus allowing you to fit the sprinkler onto smaller beds or limited turf areas.

Another specialized sprinkler uses a gear drive system to provide a range of round, square or rectangular patterns. This sprinkler works well, but the drive is subject to eventual failure if the water quality is poor. Other specialized sprinklers are designed for watering small beds.

Hose-end sprinklers offer low cost and flexibility for watering lawns and gardens. Rotary impact models are good for general use, but they must be properly overlapped. Specialized models are good in smaller areas.