LEAST EXPENSIVE FLOWERS FOR JULY THROUGH SEPTEMBER. is the slower period for the floral business.Gladiolas, Gerber daisies. Chrysanthemums, snapdragons, carnations, Roses, Orchids & alstroemeria are cheaper than in any other time during the year. AVOID flowers that grow from bulbs, such as lilies or tulips, this time of year. If they are available, they are expensive.