Daily Flex Crop Coefficient: 1 Large Oak Tree each - Front/Back Yard Zone

Hi All,

Almost have the flex down perfect. I have two large Oak Trees. One each in both my front and backyard zones that are on a moderate incline. Both trees are centered in the top 1/4 of their zones. The rest of the zone is cool season grass.

I’d appreciate a recommendation. The grass tends to stress out under the root zones to the tree drip lines going downhill. I believe an adjustment to the crop coefficient in these zones is needed. Not sure what the correct number (or reasonable ballpark) would be and any suggestions would help!

Location (Boston Area)

Matching Zone profiles:

Current co-effeicent is: 0.7

4" Cool Season Grass (Sun & Seed turf w/ bluegrass seasonally over seeded into the mix)
Mostly Sunny
Moderate Incline
Rotor Heads
Root depth: 6.5"+ set to 5.5" to match weakest areas. (under tree root zones on hill)

With Appreciation,


I’ll assume this moisture related

Well, you beak the stressed parts out to their own zone, the. Increase the co for this/these zones.

Or Increase the co for the existing zones but you run a small risk of overwatering parts of these zones.

Or Cut down the oaks.

You are loosing water outside of the model’s functions…

If it is light related, get a rye or some hybrid that has lower light requirements.

@plainsane. It’s totally moisture related and the way the system was originally designed. I think the only realistic option is to keep the trees and break up the zones like you suggested. 9 perimeter rotators with total overlapping coverage and a center rotor going 360, plus side yard rotors.


You might try putting in a custom rotor into your zone setup mode with a lower precipitation rate. I believe the default precipitation rate is 1 inch per hour. I would also increase the slope so you get more cycle and soak. I had a similar issue with my fescue. I lowered the precipotation rate to .60 and I am not getting the kind of browning before. You live in a beautiful part of the country. I lived in New England between 1987 and 1993. And it can get very hot there, too.

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Thanks, @robertokc! Absolutely right. The issue is caused by older and dense thin fescue. Had to take down another oak that was providing more shade in Spring 2015.

I had been thinking about having another rotor installed with a lower rate nozzle in the mulch bed in front of the tree with a focused rotation. I have more than enough pressure. Think you’re onto something.

I’m going to continue to aerate/over seed for the next few falls with bluegrass. It worked really well where its fully established from last fall. I’ll see if that combo does the trick. Hopefully gradually the newer turf takes over.

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Good deal. Hope it works.

Just an update and solution after talking to our irrigation company. Hybrid solution from both responses.

Backyard: Property is at the bottom of a hill on our street. Back and front yard zones are on the incline. Side yard zone is on the other side of the driveway with minimal incline. 2 heads in the Side Yard zone are in the backyard and were originally set to overlap with the backyard zone, assuming they watered on the same day. Due to the nature of the flex system, they were watering a few days apart and providing less coverage. Breaking up the Back Yard/Side Yard zone before over seeding this fall to solve that issue.

Front Yard: The addition of the custom nozzle and increase in incline is already showing recovery in the Front Yard.

Thanks All!

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