Continue to cut and insert clusters of hydrangea blossoms, balancing out the blooms from both sides of the holder.
Be sure to continue to dip each cut stem into the powdered alum before inserting into the wet flower foam.
You can quickly fill in the bouquet, rounding out for the nicely even mound of flowers as a base before inserting your other flowers.
Don't be afraid to gently spread the flowers aside, inserting more sections until the green foam is completely concealed.
You may need to place your fingers close to the foam surface and gently "work" the fragile stem into the foam. Trying to poke it hard into the foam without support may break or crush the stem.
White hydrangeas generally have a greenish tinge to them. Most fresh flowers are not "prefectly" white, blue, pink, or other. It's the blending of shades that give that lovely effect of a natural garden bouquet.