Your guests will be arriving any minute. The candles are lit, the bubbly is chilled, the coolest music anyone has ever heard is playing at the perfect volume, the flower arrangements are lush and modern, and the flower water is subtly, insidiously stinking up the entire apartment...
Stinky Flower Water (STW) happens to the best of us. It happens so slowly, so subtly, that it may be undetectable to those that co-habitate with the flowers in questions. To someone just walking into the room (or even the next room) however, the smell of STW can be quite powerful. Powerful, and icky. The only remedy is to set yourself up on a strict water-changing and vase-washing regime, and stick to it. Every morning, put your kettle on to boil for coffee or tea, dump the water from the vase (if it is not stinky, use it to water your plants), stare out the window for a second, quickly wash out the vase, refill with water, replace flowers, and continue with your day. Every other day, snip a little from the bottom of each stem. Daily flower care may seem a bit much, but it is so worth it. My mom's flowers always have freakishly long lifespans because she takes such good care of them...and no stinky water, of course!
There might be a few elements in your arrangement that will prove particularly troublesome. Ornamental kale is lovely, but it can stink up a vase of water in mere hours. Change it right before the party! Evergreen branches tend to drop lots of tiny needles into the water, thereby speeding the stinking process. The flower stock creates the worst smelling water I can imagine. When I was lucky enough to work with the lovely Cheri of Lilybelle, we lived in horror of spilling "stock-water" on ourselves. You'd just have to burn those clothes.
Change the water in your vases everyday, and you'll never again have a dinner party ruined by STW!