The difference between a seed and zonal geranium is that a seed geranium is grown from a seed while a zonal geranium is made form a cutting. That is why zonal geraniums are hardier than seed, because they have already been growing for a year or two. What about frost? Be careful if you plant your flowers too early in the season. Many people get the urge to start planting early but sometimes a late frost may damage your annuals. There is nothing wrong with purchasing your plants before the crowd, but you might want to keep them in the garage until after the last frost has past, or if you do plant them, put a sheet over the planted beds at night. This protects the plants from the cool night air.