I read the three little birds post on molasses and vid and iso have talked about molasses

the genral recomendations are once or twice durring the end of flower (one right before flush/leaching) at a strength of up to 1 sometimes 2 tablespoon per gallon

it can be used to feed the helpful beasties living in the soil (organic)
and to chemically bind to metals or minerals so they don't build up in the plant (a process called chelation)

I am using it at a much lower strength until I am comfortable with it - it takes awhile to fully disolve in the water and too much can make the soil yucky