Flushing HELP

Im about to switch my plant over to 12/12 and im using biobizz grow and bloom, and i just thought, do i need to flush my plant before i add the biobizz bloom?

Why would you. REMEMBER: even though you are going into flowering, the plants still need N, especially the 1st few weeks of flowering. I actually continue to give a 50% dose (of normal Veg strength) well into the 5th or 6th week of flowering to help keep them green and healthy. One of the biggest mistakes many make is to cut N down too much too early and plants health starts to suffer, therefore reducing resin production. Think about all the finished pic's of marijuana you see and how green some of the plants STILL are....I guarantee these plants continue to get a hearty N dose thru most of flowering.