An annual plant that can be planted a little earlier than most annuals, is the frost tolerant Snapdragon.
It is a native of southern Europe. And was grown in Roman gardens and in the vacation villa gardens where wealthy Romans built terraces overlooking the blue Mediterranean Sea.
Its genus name is Antirrhinum, which is a combination of two Greek words "anti" meaning "like" and "rhinos" meaning "nose." Children enjoy pressing the sides of these flowers to make the two tips snap open, hence the common English name of Snapdragon.
These plants will sometimes winter over in areas where temperatures stay above 10F, but they are susceptible to many fungal diseases. They like to be planted with protection from strong winds and must be dead headed regularly to keep blooming.
The flower spikes open from the bottom up and come in all colors except blue. A great deal of hybridizing has occurred with these plants and so there are now varied heights, colors, and flower forms.
Plant them in well-drained soil in full sun and water, and fertilize regularly. Snapdragons depend on bumble bees for pollination as honey bees are not heavy enough to cause the blossoms bottom petal to snap open.