Too much Nitrogen fertilizer. Stick with organics.

What plant are you asking about?

Whatever the plant is it sounds like you've overfed it.

Maybe not enough light also. Some plants won't flower if they are in too much shade.
It would be helpful to know what plant you are referring to.

could also be a late season plant and not ready to flower yet. eg asters etc.

Maybe it's a plant that doesn't have flowers - one of those low light plants like ZZ plant?