When put corn gluten on lawn
We don't and actually can't recommend the use of corn gluten to control weeds.
In the past it was primarily because it doesn't work very well and is expensive. Now however, there is a new law in Maryland that aims to prevent run-off pollution of the Chesapeake Bay and prohibits the application of excess nitrogen, and the amount of corn gluten applied to be at all useful is in excess of the legal limit.
The best way to fight crabgrass is to have a thick grass cover that prevents weed seed germination. If you don't have that, consider overseeding or a lawn renovation late this summer into fall.
If crabgrass control is warranted now, we suggest using a pre-emergent (prevents germination) application WITHOUT excess added fertilizer. (read the labels and look for the ingredient pendimethalin). It can be applied now.
Here is our lawn page, which includes best management practices, how to do a renovation, and the Maryland Turf Fertilizer law:https://extension.umd.edu/hgic/plants/lawns