Summer Irrigation: Planning and Management
By Kevin Bardsley
Implementing and maintaining an effective watering plan will give your landscape longevity and health. Here are points to consider for your summer irrigation plan.
Zone Planning and Scheduling
The Texas summer heat places demands on landscapes that require an accurate watering strategy. Each irrigation zone should be planned and programmed to have maximum water conservation and efficacy. As you plan your zones, take into account the following:
- Type of soil in the area (clay, sandy, loamy, etc.): Clay soils retain water and nutrients, and overwatering will saturate the root zone. Sandy soil has significantly better drainage, but will dry out sooner. Our white paper on mulch gives more detailed information on soil types.
- Type of plant material in the area: turf grasses for example require more water than native perennials. If you are planning a new landscape, group together plants with like-water requirements.
- Grade changes that would affect water run off: These areas are best served by constructing retaining walls or terracing the landscape. This will reduce run off and excessive water usage.
- Sun and wind exposure: Direct afternoon sun and high wind areas will require more water than their morning sun/sheltered counterparts. Set the controller(s) to water these areas when the heat or wind is at a minimum.
- Any trails, paths, concrete areas: When scheduling watering for these areas, take into account the trail/parking area’s daily usage, as well as the additional heat and stress these hard surfaces put on the landscape.
Irrigation Tools and Options
Once you have noted the conditions within the irrigation zones, plan the correct heads/distribution for each zone. Here are the most common watering methods for north and central Texas:
- Bubblers: Used for direct application watering, commonly used to water trees in turf landscape areas
- Drip: Subsurface emitters on pipes which require a longer run time, but have the least amount of evapotranspiration (a water-wise approach for hot climates)
- Micro Emitters: Most commonly used in pots where they efficiently irrigate small areas
- Pop-up Spray Heads: Most common type of residential sprinkler head, also used in commercial applications for smaller turf areas
- Rotator Nozzles: Alternative to traditional pop-up spray heads. Rotator nozzles emit small streams of water at a slower application rate. This allows soil to absorb water and reduce run-off.
- Rotors: Larger pop-up spray heads that spray a single stream. Used for larger turf areas as 15′ to 100’+ can be watered from a single head. Requires more run-time than spray heads due to application rate.
Each individual irrigation zone should have the same type of heads, which will provide consistent distribution. As examples, sprays and rotors should not be on the same zone, nor should drip irrigation be combined with sprays/rotors. If a larger rotor zone needs a few spray heads to cover a small turf area, we recommend using rotator nozzles on spray bodies in these areas, as rotators and rotors have similar application rates.
Water Timing and Quantity
Watering at the wrong time or using too much water not only wastes water but can also weaken the landscape, making it susceptible to disease. Watering mid-day or in the heat of the day is not recommended, as it increases evaporation and results in excess water usage. Shade zones should be watered in the mornings, as evening watering can allow for molds or fungi.
Increased periods of evapotranspiration (brought on by heat, heavy winds, excessive drought), will require controllers to be adjusted for increased watering times. For an average Texas summer, however, budget for 1” – 1.5″ of water per week for general landscapes, understanding some zones may have special watering requirements.
Before you set up the days to water, review your city’s water restrictions to be sure you are in compliance.
Below are the manufacturer recommendations on head precipitation rates, which serve as a good starting point:
- Spray Nozzle: 2″ Per hour
- Rotator Nozzle: 0.4″ Per Hour
- Rotor: 0.4″ Per Hour
- Drip Line: 0.42 to 1 gallon per hour (varies depending on line used)
- Bubblers: 0.25 to 1 gallon per minute
To accomplish the 1”-1.5” water application per week, each head would require:
- Spray Heads: 45 minutes per week
- Rotors and Rotators: 2.5 Hours per week
- Drip: will depend on the emitter rate of the tubing as well as the spacing of the tubing. Assuming you had a 0.6 GPH tubing and tubing at 18″ spacing with 18″ emitter spacing, the emitter flow rate would be approximately 0.43 inches per hour (requiring each drip zone to be run 139 minutes per week).
The above manufacturer recommendations are to reach the 1″ of water per week. If you are permitted to water 3 days per week, here is the daily programming breakdown:
- Spray Heads: 15 minutes per scheduled watering day (recommend splitting between two start times to minimize run off)
- Rotors and Rotators: 50 minutes per scheduled watering day (also recommend splitting between two start times to minimize run off)
- Drip: 45 minutes per scheduled watering day
The above are guidelines. Once your system runs through a complete cycle, walk the grounds and look for areas which are holding water, dry, have excessive run off, etc. There will need to be continual observation of the plant material and constant adjustment to the sprinkler system. This will maximize the effectiveness of the system and maintain the best environment for your landscape. Implementing this water-wise approach respects the environment, keeping water usage (and costs) at a minimum.
Final Checks and Issues
When checking the irrigation system, look for clogged nozzles that may be affecting the spray pattern. Lateral and drip line leaks will affect the application rate at the emitter or head. Low pressure or fluctuating pressure can also be the result of clogged drip filters or valve flow issues, as well as head to head coverage between spray and rotor heads.
Chart the coverage areas of the heads and rotors, then limit settings to be sure they are not watering hard surfaces such as walkways or parking areas.
We recommend taking an irrigation audit per zone to calculate the actual precipitation rate per hour for each watering device/zone, as well as the coverage. There are multiple variables that will affect the precipitation rate – static pressure, valve size, mainline and lateral pipe friction loss, elevation change from water source to nozzle, and quantity of heads on an individual valve.
Concluding Thoughts and Perspective
A recent report in agroecosystems states that “irrigation is arguably the most important cultural practice in the management of plant diseases, especially in the context of the quest of a more sustainable, less chemically dependent agriculture.”
If you have further questions about your landscape management or irrigation plan, feel free to reach out to us at Woodlake Outdoor. Your project is our passion!