If U want a good size bulb 'a great trick, is when there about 70% of the grow cycle, bend em over, i just walk on mine. & this will stop as much goodness going to the leaves,& put it into the bulb ,
Do weekly , as they spring back up pretty quick Also at this point, use a low nitrogen fert , or a flower nute like 6-14-12 or thereabouts if seed heads start to appear , just chop em out , the plants energy needs to be directed underground at this stage, not above