Who cares what the grass is doing, the bullet does not fly across the ground it goes high into the air. A 175gr SMK at 1000 has a Max Ord of 15 ft above the line of sight. Wind gradients are every 12 to 14 ft.
Because we have wind gradient layers knowing what the "grass" is doing is pointless. Grass, trees, leaves, etc are not calibrated to a wind speed and tell you nothing more than it is blowing. All you can say is, it's blowing and giving yourself a 2 to 5MPH window is silly when you consider that same 175gr SMK will move 10" per 1 MPH at 1000 yards. So if you say, it's 12 to 14MPH it's 20" of drift.
How you use a wind meter is to read the wind for 2 minutes solid, (at least ) it will give you the highs, lows, and average for that two minutes at which point you can calibrate your eye to the changing conditions around you. (what you see) then match those changes to the wind meter reading. from there you can note the dope for the high gusts, low lulls, and average speed so when you hear, feel or see, the wind changes in the landscape around you, you can then match that change to an actual call and adjustment in your dope that is valid.
The whole, Leaves, Grass, Etc... is pure BS that old timers like to say, they shot for 30 years on the same range over and over and want to give credit to movement of the leaves, LOL Read the leaves if you don't mind investing 20 years of trial and error.