Soak the florist's-foam shape in water following the manufacturer's instructions. Trim the carnations to about 3 inches. The 12-inch diameter wreaths displayed on the mantel require about 50 carnations each.
Insert the carnations into the forms until the surface is covered. To prolong the freshness of the carnations, store the arrangements in a cool area when not in use. Artificial flowers may be used instead. If using artificial flowers, there is no need to soak the florist's foam.