Empire turf, the company that genetically engineered this particular strain of Zoysia has different ideas.
Here is a direct quote from their website. " Maintain EMPIRE at 1-2"
Heights above 2" will reduce quality
Can be maintained at heights of 1/2" if regularly mowed with a reel mower
Rotary mowers are preferred for heights 1" or higher
Reel mowers are preferred for heights below 1"
http://empireturf.com/emp-maintenanc...elines-1.shtml