Even when I was growing up on the farm I heard the phrase that corn should be "knee high by the 4th of July." Even today we all hear about that old standard though it has not really been relevant for many decades. I think you would have to go back to my grandfather's generation where the old standard applied. Farming practices were much different back than compared to today!

My grandfather told me many years ago that they planted corn around Memorial Day. Corn is a warm season grass and it did not do well when planted early in cold and many times wet soil. In addition they did not have herbicides to control weeds back then. They would work or till the soil a couple times and kill flushes of weeds before planting corn. By later in May many weed species do not germinate any more for that season.

Today we have herbicides to control weeds. In addition seed corn companies have for many decades emphasized cold tolerance when developing new corn hybrids. Back when corn that was "knee high by the 4th of July" they were pleased with yields of 100 bushel of corn an acre. Todays standard is more like 200 bushel an acre or more!

I pulled a corn plant from one of my tallest hybrids and took it home so Louise could take my picture. That corn plant is 8 foot 4 inches tall. The corn hybrid behind the car is not quite that tall.