Need help with how long to water- taking too long to get 1/2 inch

joanncat18July 10, 2011


I am new here and pardon me if this is a stupid question or if it is covered elsewhere. I bought some new sprinklers and I am trying to improve my grass. I read that the grass needs 1 inch of water per week and I read a few places to water 1/2 inch twice a week to equal 1 inch total per week. I am using a tuna can to measure the water and it is taking many hours to fill the can. This seems like way too long. I am placing the can towards the far edge that my sprinkler hits because I figured that once the far edge got 1/2 an inch that the rest would have gotten that much or more. Also the far edge is the most brown area of the grass. I have a pulstaing/impulse sprinkler. The sprinkler has been on for over 5 hours and the can is still not full. The can is placed out in the open so there aren't any trees or anything in the way to prevent the water from going into the can.

I have read that some people get 1/2 inch of water in an hour or so. I know it depends on water pressure and the sprinkler type etc, but this seems excessive. Am I doing something wrong? Is the tuna can in the wrong spot? If you are trying to give the whole lawn a 1/2 inch, then where would you measure that in relation to the sprinkler?

Any advice is appreciated. I don't want to be over-watering either. Thanks.

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If you have a 5 gallon bucket and know how large the area is that needs to be watered, it's not too hard to get a time that will accomplish your goals.

First, time how long it takes for your hose to fill up a 5 gallon bucket. This gives you the rate at which your irrigation system puts out water.

Then, do the math contained in #1 and you're all set.

"How Much Water - If nature has not supplied water as rain applying approximately 1 inch of water is a general rule of thumb. This will give deep penetration of the soil to a depth of six to eight inches. One inch of water or rain is equivalent to 623 gallons per 1000 sq. ft. Water should be applied no faster than the soil is able to absorb it. If water begins to run off before one inch is applied, stop sprinkling until it is absorbed and then resume.

How long will applying 1 inch of water take? This depends on the size hose, pressure and type of sprinkler being used. There are several methods for determining how much your are applying.

1. Do The Math - Find the gallons per minute (GPM) flow rate of the sprinkler being used from the package of the manufacturer. Multiply the square footage to be watered by .62 gallons or 1 inch of water per square foot. Example: 1000 sq. ft. x .62 gal. = 620 gallons. This tells you how many gallons of water you need to apply to the lawn. Divide that number the GPM of your sprinkler and you can figure how many minutes to water.

2. Collect The Water - Place a cup or glass in the middle of the area covered by your sprinkler, turn water on and watch the time. Measure water in the cup until 1 inch is collected. This is the time you need to sprinkle. The best accuracy is obtained if you use several containers at different places in the sprinkler�s coverage pattern and average the results.

3. Buy A Flow Timer - Often called water timers, these units actually measure water flow. They are calibrated in 100 gallons and can be set from 100 to 1500 gallons to give you the water necessary for the square footage covered by the sprinkler. Use the formula in #1 to figure the gallons needed.

4. Test Soil - Test the soil 6" or more below the surface to make sure it is dry. Turn on your sprinkler and periodically test the soil 6" down until the water has penetrated to that depth. Keep track of how long it took and use that as the time you need to water.

Here is a link that might be useful: Watering Needs

    Bookmark   July 11, 2011 at 12:13AM
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Well I did it the low tech way and it worked fine for me:

Take 3 tuna cans instead of one and position them diagonally across from each other -- my pattern was Northwest corner, dead center, and Southeast corner.

***When you take your time measurement it's all based upon how long it takes to fill the CENTER can.***

It took my irrigation system 1/2 hour to fill the center and in that time the others were one quarter and one half filled.

Here's my lawn with watering and fertilizing:

I hope this adds some perspective to your situation. Good Luck.

    Bookmark   July 11, 2011 at 11:55AM
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