Laborers for the floriculture crew usually start out with minimal qualifications or experience. Growing cut flowers is a bit more intensive and interesting than growing other agricultural commodities, but it attracts much of the same unskilled labor. Delivery drivers, who are needed to get produce to market, must have a driver's license and a good driving record, but that's about it.
Managers, on the other hand, will need some experience and education. If you're looking to go the management route, a degree in horticulture is a must. No matter what, though, you'll probably have to pay your dues as an underling, learning the specific growing needs of a whole lot of different flowers, before you'll be able to work your way up to management.