Even if dunno what flowers she like, giving gal flowers, she will definitely be happy???
well, everyone's different. and how happy she is when receiving them depends on how much she likes you as well

there are girls who love flowers and girls who don't really care about them.
i find that gals who like flowers are usually quite happy to get a bouquet even if it's not their favourite flower, as long as it looks nice. anyway you can't always keep sending the same kind of flower lah, even if she has a fave type. gets boring.