Snapdragons are an old decorative flower, which was already known to the Romans. From genetic center around southern Spain the cultivated form was spread throughout the whole Roman empire. Nowadays remnants of these original population which all belong to the species Antirrhinum majus are found among Roman remains like temples, stadia etc in southern France, Malta, Israel and so on. The scientific name of the genus Antirrhinum was first defined by Carl von Linné (also Carl Linnaeus) in the year 1753.
Taken from The Snapdragon Home Page
The Snapdragon is a flower that has been a favorite of mine for some time. I was first introduced to the snapdragon when i was very young. I remember it very well... My grandmother always had a very large garden and I remember playing up at her house alot as a child, but what i remember most about the plants from that age in my life was her Snapdragon or Antirrhinum majus. Nowadays the snapdragon is still among my favorites. Many people like to snapdragon for the blossoms that you can pinch to make the "dragon mouth" open and close. Snapdragons come in a large variety of colors and have a faint fragrance. You can get then in roughly two sizes: dwarf varietys can range to about ten inches where a taller type can grow up to eighteen to twenty-four inches. Their was a man made variety that grew up to five feet but it needs to be staked. A single snapdragon can produce up to seven or eight snapdragon spikes on the course of a summer
Snapdragons make excellent cutflowers and excel in beds and at
the front of borders. Gardeners used to be less than enthusiastic about snapdragons
as cut flowers because blossoms tended to "shatter"--drop off shortly
after being fertilized by bees, but plant breeders have developed shatterproof
strains. Snapdragons flourish in well-fertilized soil and full sun.
Plant seed indoors about eight weeks before the last frost. Move the seedlings outside in the spring as soon as possible because snapdragons can handle a little frost.. In Zones 8-10, seedlings started in a sheltered seedbed may be moved outdoors any time in the fall for winter and spring flowering. When planting your snapdragons make sure they stand about six to twelve inches apart depending on your chosen variety. Seedlings purchased from a garden center where conditions are carefully controled will usually bloom earlier than those started at home. If possible, choose rust resistant varieties. When the plants are 2 to 4 inches tall, pinch off the stem tips if shorter but more abundant flower spikes are desired. Then, as the flowers mature, use them freely for bouquets; the cutting will force plants to produce additional stems that will bloom later in the season. Cutting The heads off of snapdragons actually helps them achieve a longer flowering period.
Sites
http://caliban.mpiz-koeln.mpg.de/~stueber/snapdragon/snapdragon.html
http://www.gardenguides.com/flowers/annuals/snapdrag.htm