Most of Illinois has been dry recently. If you can, water your lawn deeply...about 1 1/2".

You probably have a large percentage of KBG. One of the reasons KBG became so popular in Europe and then North America is because it can recover from over-grazing better than most grasses. Over-grazing is similar to close mowing.

Your lawn should recover within a week or so if you water it.

-Deerslayer

One inch is enough, and that is normal irrigation per week. You really don't have to help the regrowth because it will grow quite on its own. Right now, it is under stress from the shock so even if it turns brown all over, it will bounce back. You just don't want to let it dry out. That will add drought stress to the problem, but too much water won't help either. Keep an eye on it for a week or two for indications of disease - brown spots or signs of fungus while the rest of the grass is green again. What happens is the plants' energy will be fed mostly to the tips of blades to help them recover, leaving the lawn more susceptible to disease if such is possible in the first place, and it's possible in warmer weather. Basically, you don't have to be concerned, provided the lawn is normally cared for in the proper way.

This is exactly the reason why I suggest people weld the adjustment on their mowers to the highest position. Some well-meaning person IS going to come down the pike and do you the favor of mowing your grass at 1 inch.

Bestlawn, the energy is not sent to the tip of the leaf blade but to the band of tissue where the blade joins the sheath. From this area both sheath and blade elongate and are kept in proportion to each other. Note how the grass grows from one mowing to another but there is no change at the cut end of the blade. This is the major drawback to scalping. This tissue is removed and the only thing the grass can now do is to tiller from intact nodes below. These little tricks of Mother Nature fascinate me.

Very interesting, Ron, so let's discuss that a little further. You said, ". . . but there is no change at the cut end of the blade." Of course there is, or the blade would remain flat (cut) all the time. Bluegrass is boat-shaped and grows back into being pointed at the cut end. You're suggesting it doesn't. I was referring to what happens to the grass in a shocked state, which usually makes the tip (the cut end) turn brown. You're suggesting it would never recover and turn green again.

Can I do anything now to avoid the fungii /weeds? As I understand, when scalped it is more susceptible to weeding..So can I add CGM or anything organic to help re-growth / to prevent disease/weeding?

"Scalped" and "cut short" aren't really the same thing. If the lawn was still an inch tall, it wasn't really scalped. Scalped implies that it was cut down to the soil. If that was the case, there could be damage to the crowns etc and you might have some permanent damage. What you describe is jsut it getting mowed too short. If that is all it is, just water and wait. The grass will recover shortly without any special treatment. Since this is prime weed germinating season, you might have a few more than usual pop up in the week or 2 it will take you your lawn to get back on its feet, but nothing major to worry about.

If you want weeds to sprout, then water every day for about 15 minutes. If you don't want weeds to sprout, then do something completely different - like water only weekly.

Ok,I guess techinically it was cut very short and not scalped..But theres just yellow patches all over.
dchall_san_antonio, your advice seems to contradict previous advices before(water your lawn deeply...about 1 1/2")...
or atleast doesnt seem to complement it...
So from what I unederstand, if I do water it everyday/so,it will be back to normal in a week/2 but I will have more weeds, but if I water say weekly , I will have less weeds but slower growth, is that correct? Sorry, I am just trying to find the right compromise here...

My previous recommendation of 1 1/2" of water was for one time only. KBG normally needs about 1" of water per week which includes rain. In other words, if you receive an inch or more of rain in a week, there's no need to water that week.

I think DCHall's point was don't water every day because daily watering encourages weeds.

-Deerslayer

Dchall was responding to your question about the lawn now being more susceptible to weeds. He was kidding you to say if you want weeds, then water every day. He was not suggesting you do it, and he would not suggest doing it under any circumstances.

What your refer to as being more susceptible to weeds is simply that the lawn is now cut to such a short length that it no longer shades the soil, thereby exposing weeds/weed seeds to air and sunlight. Every plant needs those, but taller grass helps to prevent weeds by depriving them.

I was suggesting that because it could be in shock from mowing so much off at once, it could be more susceptible to disease it may have been vulnerable to in the first place. In its shocked condition, it is in a somewhat weakened state and not able to keep fighting off something it is already open to. So, just keep an eye on it.

I think we're all trying to say you really don't have to worry or do anything in particular right now except water it, which I'm sure you've done by now. I know you are concerned but don't have to be, and basically you cannot help it recover. It will do that quite on its own. If I were to suggest adding anything right now, it would be corn meal for its anti-fungal properties to help fight disease. But then, I would suggest that anyway.

I'm kinda wondering if you know what we mean by "water deeply" or "water 1 inch" or "water infrequently." Please understand no one wants you to water your grass every day. That absolutely cannot help it to recover from being mowed too low. It can only cause very awful problems. We want you to water it just 1 inch all at once, and then not again until the next week. Deerslayer is explaining you must take rainfall into consideration. Your grass needs 1 inch of water each week. With 3 or 4 tuna cans placed in various places for your sprinkler to reach evenly, time how long it takes for the cans to get just 1 inch of water in them. That is how long it will take to provide 1 inch of water to your lawn. It might be 45 minutes. It might take an hour or more. It just depends on your sprinkler system, but you want to water for that amount of time. You want your whole lawn to receive 1 inch of water, so if there are areas that do not get any water, then position the sprinkler to irrigate 1 inch in one area, and then move the sprinkler to irrigate 1 inch in the other area.

Hope I explained things a little better.

Thanks for such a detailed explanation..I guess my anxiety made me a little numb in the skull...But yes,I did understand that DCHall was kidding that water daily if you want more weeds...But I wasnt sure about the frequency of watering...
DeerSlayer and Bestlawn, your emails made it very clear..
I am starting to breathe more normally now...

Whew! Me too. I thought you had misunderstood and thought I had a typo in there.

My point wasn't well made. What you have now is a lawn that is susceptible to weeds because it is short, like bestlawn explained. The worst thing you could do now is water frequently. Weed seeds need daily water AND full sun to sprout. They are already getting full sun, so you want to withhold water, but not so much that the grass suffers.