You gotta figure out if a woman likes you at all before you go springing flowers on her. If she doesn't like you that way, you're both going to feel akward around each other, after you give them to her.
You can tell tremendous much from good conversation, if you are patient and know how to look for the right clues.Now, there are some guys who think that if a woman smiles out of politeness and makes small talk, she must be interested. She just may be showing good manners, though.
If you know how to speak to a woman, you can get her to reveal whether she likes you enough. It's going to show in her responses, her eyes, her facial expressions, etc. Don't give her flowers until you know for sure she likes you. Even then, a lot of us women see cut flowers as cliche'. Unless the flowers have a place to go. Example: you ask her for a picnic and you bring a vase, a bottle of water and unique flowers, to add a romantic touch to the picnic table.
For me, I'm going to look for more originality than a bunch of flowers and a box of chocolates.
Don't get ahead of yourself. You have to figure out if there is any interest on her part, before you go on to the next step.