I planted a row of them when I bougt this place, 1976, probably planted them in 1978. Other than pruning the low branches I haven't touched them. I also have never watered them except for the first year. Slow growing for sure as they are still not firewood size, some 20' high but no girth yet. It is great firewood and lucky is the person who runs into a scrounge of it that was planted by the original settlers.
My best srcrounges were clear cuts of dead stands killed by Locust Borer. A couple scores were a couple acres in area. Still have around 60 cord in my stash and the current project, when I am allowed to work again by the doc, is split/stack of an original settler's planting around a homestead. Some 20 cord in that one.