Flower Vases hinder the blocks from flowing.
But when you fill up a Flower Vase to its full capacity, the Flower Vase will explode and create the same effect as a bomb.

In order to fill up the Flower Vase to its full capacity, you need to match the Flower Vase with blocks of the same color for a certain number of times.
The capacity of the Flower Vase cannot be expanded and the Flower Vase cannot be removed by matching different colored adjacent blocks or blowing up Items.