Are you sure the seed was Cosmos? Sounds as if its not the seed you thought it was? but a pic would confirm that? Could you have over fed them? to much feed can produce lush growth but no flowers in some plants, but I think that is unlikely as you all have the same results. Could you have grown something like Fennel?

Thankyou for your super rapid reply! They are definately cosmos, my mum bought the seeds from Chilterns and grew the baby plants, I am sure that they are. Last year they were prolific...In one bed the soil is very poor and the cosmos are very cozy with nasturtiums, sweet peas and morning glory. In the other bed they are housed with dhalias, asters, lobelia, calendulas and variuos other summer bedding plants. This bed is one we made last year and if filled with compost, top soil and manure. Everything else has gone with a bang but the cosmos (whilst still beautiful - I love the foliage) is growing into what can only be descrided as small trees. One of them has flowered but it happened to one that was a bit leggy, the runt of the litter so to speak. As it stands, my mum is a very keen gardener and even she is stumped. I realy hope yo can help :)

As it's an annual it will flower sooner or later, IF it's Cosmos. I tend to agree with Drc, as our Cosmos, which was sown quite late, has been flowering for weeks and weeks.

Just seen your reply which was posted simultaneously. If you are sure it is Cosmos then don't worry as it's bound to flower, after all that's what annuals do otherwise they'd die out. If you have such big lush plants then they should have loads of flowers too, and later flowering is probably better as there is less in the garden as the summer goes on.

Thankyou, that gives me hope!

As long as there is enough sun, they will flower. Flowering is much delayed in very rich soil, though!

I have some cosmos grown from seed earlier in spring.I planted them out in the annual bed and I thought they might be this years failure as they grew on a ,bit frail.Then just to suprise me they started to grow rapidly a few weeks ago then a ,miserly little pink flower appeared,so a bit dissapointed I left them to there own devices.They are now the stars of my bedding a profusion of pink flowers propped up by the bizzie lizzies,I agree I think they will be alright.

I have had exactly the same issue, luscious trees and no buds / flowers, so I too have been given new hope Thank you! I'm a novice gardener and thought I was running before I could walk attempting to grow Cosmos from seed - I feared I may have omitted some crucial step in the planting process. May husband may have over nourished slightly however.