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Water and grass: what is the real need?

Post Date:07/06/2018 2:17 PM


Do you see any difference in the grasses below?

A.  Lawn A_every other day clock timer - Copy     B. 

C.     D.  



Each of these grass plots at the University of Minnesota Turf Grass Lab receives the same amount sun and same mowing. However, each plot receives different amounts of water. Some are irrigated every other day. One only gets water when it rains.   

How much is needed?

Often, we think grass needs more water than it really does. As you can see from the photos, the rain we get is enough to keep the grass healthy and green.  The rule of thumb is that grass needs 1 inch of water a week. That inch can come from rain or a hose.  During summer of 2017 there was only 1 period of time where we didn’t get sufficient rainfall to meet grass needs. This summer we are getting even more rain.

Over watering a lawn creates problems. Soil can only hold so much water.  Excess water runs off carrying pollutants to lakes and rivers.  It can also increase your risk of basement flooding.  The water used for irrigation is the same water coming out of your tap. It’s treated drinking water.  Irrigation can stress groundwater supplies which is where we get our drinking water from.

Use less

Have an irrigation system?  Simply shut it off until the weather dries up and we aren’t getting 1” of rain a week .

Other tips

  • Mow high.Taller grass = deeper roots. Deeper roots are more drought tolerant.
  • Condition your grass roots with deep and infrequent watering. Allow soil to dry to near wilt before next cycle. Gets grass prepared to survive drought.
  • Reseed with lower maintenance grasses such as fine fescues including hard fescue, sheep fescue, creeping red fescue and tall fescue. These are lower maintenance and drought tolerant, plus do very well in both sun and shade.

Here’s a look at what the differences in watering for each plot shown above.

A. Irrigation system set to water every other day with clock timer

B. Irrigation system set to water every other day with rain sensor

C. Irrigation system set to water every other day with soil moisture sensor

D. Irrigation system manually turned off and on

E. No irrigation. Rain only.



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