To arrange flowers in a tall vase, choose flowers with long stems, and cut the stems so they are no longer than 1 1/2 times the height of the vase. Place the greenery in the vase, crisscrossing the stems of the greenery to form a grid. Arrange the flowers in a traditional triangle shape, placing the flowers with the largest blooms along the bottom edge of the arrangement. Cut the stems as needed while arranging the flowers.
To create a traditional triangle-shaped bouquet, place the flowers with the longest stems in the center of the bouquet, and taper the flowers according to the length of the stem and the size of the bloom. To create an arrangement with a modern look, choose one type of flower, and do not add greenery to the vase.
Instead, cut the stems so the flowers form a dome with the tallest flowers in the center of the bouquet. Add enough flowers to completely cover the mouth of the vase, and cut the stems short enough so that only the flower heads are visible.
Another technique involves separating the flowers into four or five bundles, securing the bundles with clear rubber bands, and placing the bundles in the vase. Use one color, such as a bouquet of pink carnations, to create a modern display.