Sunflowers that have been cut as cut flowers, are usually harvested during a very early blooming stage, so that they will have their longest blooming life in the vase.
The cut sunflower harvested early in the flowering stage will not have the ability to go on to develop seeds, which requires a lot of energy from the plant.
However if by some chance your cut sunflowers were harvested at a later stage, after they developed seed, then there may be a chance that you can get some viable seed.
If you purchased them in a store or at a farm stand for instance, chances are that they would have been picked at too early a stage to be able to produce seed before cutting.
While the sunflower is growing in the field, exposed to pollinators and growing on it’s roots, it is much more likely to produce seeds, compared to a sunflower cut as a cut flower.
There are pollenless varieties however that produce very little to no pollen.Therefore these varieties will produce little to no seed, even when left to mature on the plant.
Enjoy your cut flowers in all their beauty. If you are looking for sunflower seeds, keep the flowers in the field, and harvest at the end of the season!