I run all my lights on 240V outlets. each one is on its own 20A circuit. It is a little overkill IMO, but I can always double up on breakers. My flower room has 4 600s as well. If I were to do it again instead of having 4 outlets on separate breakers I would just get a light controller, and wire it to the panel. That is what I would suggest, if its an option, but you would need an electrician to tie it in to the panel if you dont know how to do that.
First step is isolate the breaker to see amperage available.