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Factors to consider when formulating a watering schedule for your lawn and shrubs.

  •  Is the area subject to intense sun, shade or a combination of both?
  •  Is the area flat, sloped or a combination of both?
  •  Is the area subject to windy conditions?
  •  Is the area in close proximity to the residence or foundation?
  •  Is the area well drained?
  •  What is the soil type?

In many cases, zones will be a combination of these factors.  A watering schedule has to be “fine tuned” through the owner’s observation of the different areas of his lawn and shrubs.


When establishing a start time for the watering schedule, consider factors such as; water pressure, wind, evaporation, and foot traffic.  Studies show that the optimum time to run your system is between 2:00 and 10:00am.


It is generally agreed that your lawn and landscape benefit from deep watering with time in-between to allow the soil to dry sufficiently.  This will promote deep root growth.  However, the high clay content of soil in the St. Louis area does not allow extended run times without runoff or puddling, which wastes water and can damage your turf.  Therefore, a watering frequency of 2 to 3 times a week should be sufficient.  Under extremely hot and dry conditions increased frequency of watering may be required.

Helpful Hint; A beneficial practice to eliminate run-off or pooling during a watering cycle is to split the watering time in half and create a second start time right after the first cycle is complete. This allows time for the water to percolate into the soil. This is called “Cycle and Soak”.

Watering Suggestions

Lawn Areas

The following are suggested run times for turf zones based on 3 start times a week to apply approximately 1 inch of water

  •  Rotary sprinkler single spray (20′-45′ radius): 45-60 minutes
  •  Rotary – multi stream nozzle (13’-30′ radius): 45-60 minutes
  •  Fixed spray heads (2′-15′ radius): 15-20 minutes


Consult your landscaper or nursery before setting your run times.  As a rule, shrub zones should run only once or twice a week, especially shrub zones located near foundations or barriers.  These areas do not drain as well as open exposures.

Drip Irrigation

If your system uses in-line emitter tubing for shrub bed irrigation; a good starting point is a 1 hour run time, once a week. For larger trees and shrubs a longer run time would most likely be required.

Drip zones for container or window boxes require a much shorter run time. Turn the zone on manually and wait until you see water coming from the bottom of the container. Note the times it took and set the run time just short of that.


Because of their shallow root system, annuals require a more frequent, but lighter application. However, in many cases annuals are planted alongside perennials or shrubs, in which case the owner must find a happy medium, or resort to hand watering one or the other.

NOTE:  The above run times are very general in nature.  They are presented as a guideline only.  Green Turf can calculate precipitation rates more specifically for those individuals who desire such.  Precipitation rates vary among irrigation systems dependent on pressure, system design, head type and nozzle size.  The run times shown should yield approximately 1 inch of irrigation weekly varying with individual systems. Increase or decrease run times and/or frequency depending on weather conditions.  Be careful not to overwater your turf and ornamental plantings.  Overwatering usually results in more damage than underwatering.