Stiff long-stemmed roses can seem as generic as a drugstore valentine. But a few flourishes transform the cliche into a caress. The impromptu charm of a variegated rose (here, white-and-pink 'Henri Matisse') highlights the intensity of its crimson companions.
Line a container with plastic wrap. Using floral adhesive, secure frog in container. Measure and make note of distance from center of frog to rim of container.
Fill container two-thirds full with tepid water. Add a packet of flower food.
Cut stems of 3 or 4 red roses slightly longer than frog-to-rim distance. Remove foliage from parts of rose stems that will stand below water level. Insert stems along perimeter of frog.
Cut 3 or 4 more red-rose stems to same or longer measurement, and insert at center of frog.
Cut remaining roses, varying stem lengths as desired, and fill in arrangement, creating a loose dome.