Snapdragons bloom in the spring, according to the About.com's gardening expert. They will bloom best when they are planted in full-sun to partial-shade conditions. Snapdragons are poisonous flowers, so care should be taken when handling them.
There are both tall and dwarf varieties, so if a size is preferred, check the cultivar. The tall spikes of the flowers bloom from bottom to top. Snapdragons can be a single color or bicolored and are available in a variety of colors. In USDA Hardiness Zones eight and nine, they can be a perennial. However, they are an annual in all other zones.