Can plants be sterile?

[Arden Sage]

I sowed some cosmos "seashell" seeds earlier this year and chose the best 5 to plant up in the garden, spacing them accordingly in the same bed. Aside from the fact one of them turned out to be Cosmos "Purity" and one being eaten by slugs three grew well. But ... of those three, only two have flowered. The other one has grown beautifully. It is bushy, healthy and lots of green stems and leaves but not one single flower bud. Nothing.
So, is this a "sterile" plant?
Or, has something else caused it?

 

[Tetters]

Yes some plants are sterile, and can only be propagated from cuttings, but I am not sure about cosmos - I`ve never grown it. Sounds like yours might need a good talking to!

 

[cpp gardener]

Just be patient, when it decides to flower it will be huge and you’ll be stunned at the color. I’ve grown some that took their own sweet time to do any blooming and WOW! the wait was worth it. Flowers all over the place on a huge plant. You could try using some bloom booster kind of fertilizer if you want to coax it along. Just follow the directions.

 

[cpp gardener]

Just checked out Cosmonaut’s post in Other Plants and saw a 10 foot one that’s just now blooming. Patience is a virtue, especially for gardeners