It is a simple issue of supply and demand. People tend to want certain flowers at certain holiday times. This can create a large demand for specific types of flowers. Take Valentine's Day for example. More than 100 million roses are typically sold for Valentine's Day, which falls in the middle of winter. Growers work very hard after their Christmas cuttings to produce a crop for Valentine's Day. One long stem rose means sacrificing many other blooms, extra labor must be hired at every production level, there are higher heating costs and additional transportation and delivery are needed. Each of these factors contributes to the proportionate cost of flowers at Valentine's Day.