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Senior Member


Thursday, June 7th 2012, 12:20am

Hunter pgp. dry patches of grass

I have hunter pgp 4" at the corner. There is a slight incline where the grass is laid.

there's a dry patch within 5 feet radius of the sprinkler, like it's not getting water.

I turned on the sprinkler, and it appears to be spraying normally.

This is not a current picture. This was when the sod was just installed. But the dry patch is circled, and the sprinkler is marked with arrow.

I don't know how to remedy this


Supreme Member

Posts: 5,331

Location: Metro NYC


Thursday, June 7th 2012, 8:03am

If you don't have head-to-head spacing, then you need to first try tweaking the diffusing screw to break up the water stream a bit. Failing that, you re-nozzle every head in that zone with a nozzle one size smaller, which raises the zone pressure and improves the spread of water.


Thursday, June 7th 2012, 8:34am

First verify your coverage.

I've seen a good bit of this type problem in our area. We had that severe drought last year and these dead circles started appearing. ALWAYS next to concrete.
Everything else failing, we took soil samples and sent them to a local university to be analyzed.
It most cases the soil in that area was different from the rest of the yard. Far less porous, usually with a different chemical make up than the rest of the yard, often way too much sodium but not always.
Basically the soil could not absorb the water as needed and the nutrient balance was off, sometimes with unwanted chemicals.

This only showed during the drought as everything stressed and weak areas failed. The only theory we have at this time is that during original construction or remodeling or street repair or something some material was stacked there that leached into the soil.

Our quick fix has been to either remove/replace or to till in good soil and and set up an ongoing treatment plan.


Senior Member


Monday, June 11th 2012, 2:33am

I don't think the sprinkler installer put them head to head.

Would blue nozzles help in my case, since the grass is dead near the sprinkler.. ?

based on the birds eye view, the 2 outside sprinklers would not reach each other...

This post has been edited 4 times, last edit by "pman" (Jun 11th 2012, 3:41am)


Supreme Member

Posts: 309

Location: Northern New Jersey


Monday, June 11th 2012, 8:21am

Try what Boots says.


Senior Member


Saturday, June 16th 2012, 12:27am

oh man

I just looked at the sprinklers again, and the installer put in PG J's. Not pgp's.

Will switching to PGP's in the front part of the lawn help water it better?

Can I have PGJ's and PGP's on the same station ?

all my pipe must be 1/2" pvc. Can a 3/4" pgp be put on there?

This post has been edited 1 times, last edit by "pman" (Jun 16th 2012, 12:37am)


Supreme Member

Posts: 309

Location: Northern New Jersey


Saturday, June 16th 2012, 6:29am

You maybe able to mix as long as the precipitation rates are similiar.

But firt try new nozzles at least on one or two heads. If your installer did not give you the sets, they are very cheap to buy.

If nothing works, install an extra head as long as you have capacity.




Saturday, June 16th 2012, 8:08pm

your pipe not necessarily 1/2". It's just PGJs have 1/2 " inlet


Senior Member


Sunday, June 17th 2012, 7:53pm

your pipe not necessarily 1/2". It's just PGJs have 1/2 " inlet
I hope so. I looked at the rainbird control valve today, and it appears it is 3/4"

I finally took a picture of the grass today. See all the grass near the corner sprinklers are spotty and dead.

I don't think the PGJ's are powerful enough. If it's 3/4" pipe, I think it would be best to upgrade the front rotors to PGP's with 2.5 nozzle. Or perhaps put a 4th PGJ on the station in the front center of the lawn ?

The lawn is 35ft wide.

I would have to go all the way up to 5gpm PGJ nozzle to cover that.

For sure, the installer did not put the front corner sprinklers head to head. I only have 2.0gpm nozzles on there right now. That's only 25ft.

This post has been edited 2 times, last edit by "pman" (Jun 17th 2012, 8:33pm)


Supreme Member

Posts: 309

Location: Northern New Jersey


Sunday, June 17th 2012, 8:48pm

Where do you live and how much water does the grass get. For example, in NJ it's 1 inch per week. If you aren't giving it enough water and since you have a slope.........if that dirt is hard packed the water may just run off...need to fix the soil...maybe peatmoss addition.

Thinking to add a PJG in the middle with the same precip rate is the way to go.

Cantest. Get same size cans like tuna or cat food. Place where you have good grass and bad grass. Run system. If you have all similar levels in the cans, it's a soil problem. If bad grass levels are low compared to the good, add a head.

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