A topiary is most often a shrub that has been pruned into geometric or animal shapes. One of the most common is a sphere, or ball, on a tall trunk. You can arrange flowers as a topiary for an unusual center piece, as a dining room table accent or just for fun. You can learn how to make a topiary flower arrangement--it's not difficult but does take time and patience.
Carve the floral foam into a ball shape. The ball should be about half the size of the finished topiary. If the foam isn't large enough, tape two or more pieces together. Soak the foam in water for at least 30 minutes. Remove and let drain in a bucket or sink.
Cut an inch off the stems of the flowers and place the flowers in ice water for at least 30 minutes, preferably an hour.
Fill a container with dry floral foam used for dried flower arrangements, packing it tightly in. If necessary, stabilize the foam with hot glue. Push a straight branch into the foam. Hot glue around and into the hole. Place sphagnum moss over the floral foam to hide it.
Cut the flower stems from 1 to 3 inches depending on how big the floral foam ball is. All stems should be the same length and cut at an angle. Start at the top of the ball of floral foam, inserting the stems of the flowers close together. Continue inserting the stems until the ball is almost completely covered with flowers. Leave a 3-inch diameter gap at the bottom of the ball.
Press the ball onto the top of the branch in the middle of the 3-inch gap.