Cut a 2-inch tall piece of floral foam, and set it down into the container. If using see-through glass, you can omit the floral foam and use glass marbles. Fill the container half-full of water.
Cut one gerbera daisy stem under water at a 45-degree angle with a sharp knife. Cut the stem to a height of 5 inches, which is for a low, more compact floral arrangement. Use taller stems for a high centerpiece. Insert the stem in the center of the container.
Cut two more gerbera daisy stems at 1/2 inch to 1 inch shorter than the center flower. Insert the stems at an outward angle from the first flower.
Add sprigs of bear fern, leather leaf or in-season greenery to the centerpiece. Add more flower stems for a larger, fuller or taller centerpiece.
Tie a piece of ribbon around the container, or make a bow to set into the gerbera arrangement.
Set the centerpieces on the guest tables. Carefully add more water to the container until it is two-thirds full.