So, you are of that kind of odd people who like keeping fresh cut flowers at home.

I'll give you this tip so, you can enjoy them for much longer.

1.- When cutting the stems, the cut should be slanted. This way the surface to absorb water will be bigger (imagine a thin bar of salami. If you cut it slanted the slices will be bigger).

2.- Change the water daily. On the changed water pour about three drops of bleach. To do it easily with no excess pour the bleach first into the bottle's cap (watch it's plain bleach not any bleach with any kind of detergent added, this would be very bad for them). The bleach will kill the germs you can find even in the best quality drinking water. Water should be at room temperature, not very cold not very warm either.

With these simple guidelines you can make them last for up to three times longer.