Liquid iron apps all get watered in. If you plan on using it as a foliar app, allow it to sit on the grass for ~4hrs. You can also water it in immediately as a soil applied application of iron.

 

4 hours after application if foliar or if applied later in the afternoon let it stay overnight, turn the irrigation on long enough to wash it off the blades, the following morning

 

Maybe they are watching this forum. Have gotten 2 responses from them since I posted this. They recommended watering in 24 hours after application for a spray app.

I did an overseed, should this play a factor in how long I wait to water in? This is liquid so I will be spraying.

 

Your new grass will blend in as it matures. Don't expect iron to make things even.

New grass is always lighter and darkens as it matures.

 

@Harts the problem is some of my old grass is lighter :|. Trying to see if it darkens so I can figure out whats Poa now rather than the Spring.

 

@Harts the problem is some of my old grass is lighter :|. Trying to see if it darkens so I can figure out whats Poa now rather than the Spring.

I'm not saying not to spray iron. I'm only telling you not to do it with the expectation that your new and old grass will blend, which I thought was the original question you were asking. Perhaps I misunderstood the reasoning.

 

Sorry, wasn't very clear. Basically goal is to see if I can get the lighter grass to darken up to rule out massive Poa infestation, but also don't want to torch my new grass.