Cosmos failure.

I’ve often found that the larger variety flower later in the season and go on until the first frost. Maybe there’s hope yet.

Half of mine are like yours Nandalot ie tall and no flowers, the other half are shortish and blooming beautifully - all from the same packet of seeds. I think perhaps I didn't pinch out the tops properly when they were seedlings to allow them to be more bushy.

I've never got round to growing Cosmos (though I like them) but this was said to me from an avid gardener - there's been 'a bad lot' of seeds this year and many haven't flowered.

A garden centre near to where I used to live planted some near their entrance. They failed to flower so they've thrown them out. Perhaps they'll be better next year.