A Betta fish will not be at home in a flower vase. Please rehome your Betta to an appropriate aquarium. Bettas like slow moving shallow water. Remeber Betta fish need some sort of filter for filtration so he will be healthy. Also you need an aquarium so you can add a heater and keep the Betta happy.
I rescued my betta who was in terrible condition at Petco. A Petco employee looked at the Betta fish I chose and told me to pick another one cause he said the one I picked out was unhealthy and would die. Well I was determind to rescue him from his little cup. I took him home and got him a breeder net and mounted it in my 55 gallon tank. Then I added the two fake plants that came with the breeder net and took little bit of gravel from the tank and added it to the breeder net. Next I put a few peices of duckweed and added a plastic "betta" hamock leaf which is suction cupped to the top of the lid on my tank. The betta loves having the hamock leaf right above his breeder net. He actually will chill on the plastic leaf at times. Also my betta is happy in his little area cause I have even seen him make a few bubble nests. I have had my Betta for over 4 months now. He has gotten brighter in color, his fins have grown and he has gotten bigger. He is doing so good and looks very healthy. Hope your betta thrives just as mine has.