I was reading in Jorge Cervantes grow bible that soil temperatures above 75 degrees can damage roots... is this true?

Seems like it'd be really easy to have soil temps above 75 degrees when you're working with an HPS shining right down at them. Also, if you've got bacterial reactions going on in there I'd imagine it could get quite a bit hotter! What do you guys think?
lampost Reviewed by lampost on . Soil temperature above 75 degrees? I was reading in Jorge Cervantes grow bible that soil temperatures above 75 degrees can damage roots... is this true? Seems like it'd be really easy to have soil temps above 75 degrees when you're working with an HPS shining right down at them. Also, if you've got bacterial reactions going on in there I'd imagine it could get quite a bit hotter! What do you guys think? Rating: 5