Cornflowers - how many seeds?

I’ve grown these a few times but I can never recall what made some work better than others?

I put about a dozen seeds in each of these small 3” pots. Will each of these be enough to be potted in to a nice outdoor 9” pot? Or for a 9” pot do I need a lot more seeds?

I can’t recall pinching these out before... is this a good number of seeds as long as you pinch out to make them bushier?

 

I've never grown them in pots, they have always been directly sown into the borders. They are then left to grow without me doing anything apart from watering if necessary. I sow 100s.

 

Similar to Upsydaisy. I find that annuals and half hardy annuals are best when sown direct into the garden, they don't like being disturbed.

I have my own theory on this. Annuals IMO have this kind of inbuilt mechanism. Their pupose is to grow fast, flower and set seed and die. Whereas perennials and biennials have that extended period to grow, mature, seed and produce a root base that will grow again next season.