Hold an uneven number of white hydrangeas, such as three, five or seven blooms, in your nondominant hand. Arrange the blossoms so the top of the bouquet forms a rounded shape. For three hydrangeas, cut the stems all the same length. For five hydrangeas, arrange the bouquet so that one bloom stands 1 inch or more above the others at the center. For seven hydrangeas, place three of the blooms at the center and the other four blooms 2 to 3 inches lower than the three central blooms. Cut the stems at a 45-degree angle, leaving 3 to 4 inches of stem below your hand.
Insert accent flowers if desired. For example, put a single rosebud, orchid or anthurium between the hydrangeas to add color and dimension to the bouquet. Anthuriums are long-lasting heart-shaped flowers. Add accent flowers 2 to 3 inches apart in a row below the hydrangeas to add more color and volume to the bouquet, if desired.
Slip filler flowers such as baby's breath or St. Anne's lace between the accent flowers for a lacy border below the crown of white hydrangeas.
Wrap the stems with floral tape, beginning 1 to 2 inches below the blooms, to create a finished appearance. Wrap the tape so it overlaps itself in a spiral, stretching the tape gently as you apply it all the way to the ends of the stems. Cut the tape at an angle and press it to itself against the stems.
Tie a ribbon 2 to 3 inches below the hydrangeas. Create a simple bow the same way you'd tie your shoes, or make multiple loops for a larger bow. For multiple loops, make the two loops you'd use to tie shoes, pull the ribbon firmly to anchor them and then create the next two loops. Repeat until the bow is as full as you like. Cut the ends of the ribbons to the desired length, up to 18 inches for a streamer effect.