Determining the optimal amount of time to leave your sprinkler in one location depends on several factors. The water output of your specific sprinkler, the type of grass or plants you’re watering, weather conditions, and more all play a role. With some basic information, you can calculate a rough guideline for runtimes to help ensure your lawn and landscaping get the right amount of water.
The Basics of Sprinkler Runtimes
Most lawn and gardening experts recommend watering your yard for longer periods, but less frequently. For example, instead of watering for 5 minutes every day, aim for 20-30 minutes two or three times a week. This allows the water to penetrate deeper into the soil, encouraging grass roots to grow downward rather than shallowly. Deep watering promotes healthier, more drought-resistant turf.
As a general rule of thumb, you want to apply around 1 inch of water across your entire yard each time you water. To measure this, place empty straight-sided containers (like tuna cans) in various spots and run the sprinkler system. Check how much water accumulates in the cans after 20-30 minutes. Adjust run times accordingly so each area receives around 1 inch of water.
The amount of time needed to disperse 1 inch of water depends on your sprinkler’s precipitation rate. This is simply how much water it puts out in a certain time frame. Most lawn sprinklers have precipitation rates somewhere between 1/2 inch and 1 1/2 inches per hour. Rotor sprinkler heads typically have lower precipitation rates than spray heads. So if your system includes a mix of spray heads and rotors, you’ll need to run stations with rotors longer to output the same amount of water.
Calculating Your Sprinkler’s Precipitation Rate
Figuring out your sprinkler’s precipitation rate is easy:
- Place several empty tuna cans or containers throughout one zone or station of your sprinkler system.
- Run that zone for a set amount of time, such as 30 minutes.
- Measure the depth of water in each can, in inches. Calculate the average depth.
- Divide the average depth by the number of minutes run. This gives you the precipitation rate per hour.
For example, say you run Zone 1 for 30 minutes and measure the following depths:
- Can 1 = 1.25 inches
- Can 2 = 1 inch
- Can 3 = 1.5 inches
The average is 1.25 inches. Dividing by 30 minutes gives a precipitation rate of 2.5 inches per hour. This means you’d need to run Zone 1 for about 24 minutes to disperse 1 inch of water (since 2.5 inches are output per hour).
Perform this test on each zone or station to determine individual precipitation rates. It may also be helpful to create a simple table or chart to record the data for reference.
Factors That Affect Watering Times
While the precipitation rate test gives you a baseline, there are many variables that can alter how long you need to run a sprinkler in one spot.
Type of Grass or Plants
Some grasses and plants need more frequent watering than others. For example, cool season grasses like bluegrass require about 1 to 1.5 inches of water per week. Warm season varieties like Bermuda grass need slightly less at 1 to 1 inch weekly. Other plants and shrubs may need watering just 1 to 2 times per month.
Weather and Climate
Hot, dry, or windy conditions cause soil moisture to evaporate faster. Run times may need to be increased by 25% or more during periods of drought or extreme heat. Reduce times during cooler, wetter weather when less water evaporates between waterings.
Soil Type
Well-drained sandy soils require more frequent watering with shorter run times. Heavier clay soils stay moist longer but require occasional deep soaking. Loams are somewhere in between. Get to know your soil’s characteristics when scheduling irrigation.
Slope and Exposure
Sprinklers on slopes or elevated areas will need to run longer to penetrate the soil. South or west facing exposures may dry out faster as well. Consider adding 5-10 minutes in these situations.
New Seed or Sod
Freshly planted lawns have very shallow roots and need frequent light watering to establish. Water new sod for only 10-15 minutes up to 3 times daily until rooted. For newly seeded lawns, water 2-3 times daily for 5-10 minutes to keep the seedbed moist.
Time of Day
The best time to water is early morning, ideally between 4-10am. At this time, evaporation and wind are minimal. Avoid midday watering which can scald plants and evaporate before penetrating the soil. Nighttime watering also increases fungal disease risk.
Sample Watering Schedule
Here is an example summer lawn watering schedule based on average conditions:
| Zone | Precipitation Rate (in/hr) | Run Time for 1 Inch | Watering Frequency |
|---|---|---|---|
| Zone 1 – Front Spray Heads | 1.5 in/hr | 40 minutes | 3 times per week |
| Zone 2 – Left Rotors | 0.75 in/hr | 80 minutes | 2 times per week |
| Zone 3 – Right Rotors | 0.75 in/hr | 80 minutes | 2 times per week |
| Zone 4 – Back Spray Heads | 1.5 in/hr | 40 minutes | 3 times per week |
This schedule applies about 1 inch of water across the whole yard, taking into account different precipitation rates. Frequency is higher for zones with spray heads that moisten grass surfaces. Run times are longer for rotor zones that supply deeper watering.
How to Determine When to Move Sprinkler to a New Spot
In addition to running each zone the right length of time, you also need to know how long to leave a sprinkler in one area before moving it. Here are some tips for determining sufficient soak times:
Observe Soil Saturation
Periodically lift a section of grass while the sprinkler runs. When you see puddles or water pooling on the surface, the soil is saturated. This usually occurs within 30-60 minutes depending on soil type.
Use Tuning Forks
Watering tuning forks are tools you stick in the ground that show when the soil is fully moistened 8-12 inches deep. When the indicator turns blue or green, it’s time to move the sprinkler.
Use Cylinder Catch Cups
These measure water output and help determine uniform coverage. Move sprinklers once the level reaches the recommended depth for your soil type, typically 6-8 inches.
Invest in a Smart Controller
Smart irrigation controllers adjust run times automatically based on weather and plant needs. Upgrade to take the guesswork out of watering schedules.
Watering New Sod
Freshly laid sod requires extra frequent watering to take root in the new soil. Follow these guidelines when watering new sod:
- Water immediately after installation and for the next 10-14 days.
- Soak new sod thoroughly so that moisture penetrates 4-6 inches into soil.
- The first week, water daily or every other day for 10-15 minutes per zone.
- For weeks 2-3, water 2-3 times weekly as needed to keep soil damp but not saturated.
- After 3 weeks, water established sod according to normal lawn watering schedules.
- Avoid foot traffic on new sod for at least 2 weeks.
Pay close attention to keep sod consistently moist. If allowed to dry out, new sod will shrink, brown, and possibly die. Adjust run times and frequency depending on weather, monitoring soil moisture carefully.
When to Water Vegetables and Flower Gardens
Vegetable gardens and landscape plantings often need watering on different schedules than lawns. Here are some guidelines for watering gardens:
- Vegetables – Water when top 1-2 inches of soil are dry. Most vegetables need around 1-2 inches of water per week from irrigation or rainfall.
- Annual flowers – Water when top inch of soil is dry to the touch. Most annuals need 1-2 inches of moisture each week.
- Perennial flowers – Water when top 2-4 inches of soil become dry. Goal is to keep soil moist but not saturated.
- Container plants – Water when top 1-2 inches of soil become dry, usually daily. Container plants need more frequent watering.
For gardens, aim to water deeply and less often. Vegatables and flowers develop stronger, healthier root systems with occasional deep irrigation versus frequent light sprinklings. Allow soil to partially dry between waterings.
Adjusting Your System
Setting up your sprinkler system to efficiently water all your yard’s zones takes some trial and error. But a little bit of maintenance and adjustment goes a long way.
Inspect and Adjust Sprinkler Heads
Regularly check heads to make sure they’re working properly and aligned to distribute water evenly. Keep spray nozzles clean and clear of grass or debris blocking output. Adjust heads as needed if you notice dry spots.
Perform Catch Cup Tests
Do occasional catch cup tests, especially after making changes, to ensure water is being applied uniformly across each zone. Make adjustments to timers and heads as needed.
Account for New Additions
Did you install new sod or plant a garden bed? Add extra run time to that area. New landscaping elements need morefrequent watering until established.
Respond to Seasonal Needs
Your landscape’s water needs change over the seasons. Increase frequency and run times during summer’s heat. Cut back during cool, wet spring and fall months.
Signs It’s Time to Adjust Watering
Monitor your lawn and gardens and adjust watering frequencies and run times as needed based on these signs:
Wilting/Drooping Leaves
Plants and turf that aren’t getting enough water will often wilt or droop. Increase watering frequency if you see these symptoms of under-watering.
Dry, Crunchy Grass
When foot traffic leaves lingering footprints or grass blades are dry and crispy to the touch, it’s a red flag more water is needed. Lengthen run times.
Weeds
If weeds are popping up, it may be a sign your lawn is being under-watered. Deep, infrequent watering helps grass outcompete weeds.
Mushrooms or Fungus
Overly moist soils can lead to fungal growth like mushrooms. Let soils dry out more between waterings to remedy.
Runoff or Puddling
Water pooling on hardscapes or runoff into storm drains wastes water. Shorten sprinkler run times if you notice these issues.
Dry Spots
If some areas seem dried out while others remain moist, your system may need adjusting to ensure uniform coverage.
Conserving Water
There are also some ways you can tweak your irrigation system to conserve more water:
- Water in multiple cycles, allowing time for water to absorb between rounds.
- Water in the early morning or evening to reduce evaporation.
- Adjust spray nozzles to prevent overspray onto pavement.
- Let your lawn grow a bit taller – longer grass retains moisture better.
- Plant native and drought-tolerant plants that require less watering.
Upgrade to Smart Technology
The latest innovation in irrigation is smart controllers. These wi-fi enabled systems sync with local weather forecasts to automatically adjust your system’s run times and frequency based on changing weather. Smart technology takes the guesswork out of watering and saves significant amounts of water compared to old-fashioned timers.
Hiring a Professional Irrigation Audit
If adjusting your system still leaves dry spots or other issues, it may be time to bring in the pros. Professional irrigation audits involve a detailed inspection and tune-up of your sprinkler system. An audit can identify problems and help improve efficiency. Expect to pay around $75-150 for this service.
Look for an irrigation pro certified through a program like the Irrigation Association. Audits normally involve:
- Pressure, flow rate, and precipitation rate tests
- Checks for leaks, clogs or misaligned heads
- Adjustment of spray nozzles and irrigation times
- A summary report with recommendations
Addressing any issues discovered during an audit can improve sprinkler coverage uniformity by 20% or more. Your system will give your yard the right amount of water in all spots.
Conclusion
Determining adequate sprinkler run times for each zone in your system takes some legwork up front. But sticking to schedules based on your landscape’s needs, soil type, and system output will pay off with healthier plants and efficient watering for the long run. Be prepared to make adjustments as the seasons change or you add new plantings. And take advantage of smart technologies or professional audits to improve your system’s performance over time.
