Posted: 24/08/2012 at 00:15
Frstly your containers are to shallow to produce a reasonable crop.
New spuds grow off the stem of the growing foilage and if most of the foilage is above the level of the soil you won't get many spuds, a deeper pot means you are earthing up for longer and the plant takes longer to reach the surface or the point were it wants to flower . The plant in August will think due to the heat and light it needs to reproduce so it will flower, earthing up slows down this process because the plant hasn't produced enough foilage above the ground to think it's being threatened.
Put it down to experience, you can't stop them flowering, wait for the foilage to die back then pick your spuds. Plant in deeper pots next year or plant a little later and see how near Christmas you get this is third time lucky for me.
Other poster may have a different view.