According to the online Lorain Public Library System's History of Lorain, it was clipped in time for Memorial Day, 1950.
If I remember correctly, it was in the early 2000's during his first term that Mayor Craig Foltin, tired of the by then shabby appearance of the half-century-old hedge, had it replaced by the one currently facing West Erie, a little bit to the east. (That one is looking a little weather-beaten as well these days!)
The original LORAIN hedge was another one of those things, along with the giant Easter basket and the Victory Park big "V", that made a drive along West Erie Avenue interesting to a kid growing up in Lorain in the 1960's.
Here's the same view today.
And here's the newer version just a few hundred feet to the east.