For easy design mechanics use clear waterproof tape, this grid will provide support for the flower stems and is essential when designing in cube vases.
Create a grid using 3-4 strips from side to side, like a tic-tac-toe board. To ensure the strips stay in place wrap a final long strip all the way around the top of the cube.
Fill the cube with preservative water and begin by placing your draping stems. Just pick a square in the grid and set the stem in place. The grid allows you to use almost any material.
Tuck in the tulips and hyacinth in next, still using the grid group like blooms together for a more modern look. Make sure it is beautiful from all sides, and you are ready to enjoy!