cosmos not blooming

there cosmos has much green and on flowers.
can anyone tell me why?

Such lovely foliage Lia. I've no idea why you've no flowers....unless you've not been feeding them right. Try some tomato food...that usually helps?

thank you Karen., I'll try with tomato food!
the strange thing is that some small cosmos grown themselves in pot near other plants have flowers and these I've sow I'm a large pot are only green!

they keep growig tall, about 2mt! I added food,I made them soffer some dryness, and now, maybe......I can se some timid buds!