Snapdragons are a cool season bedding plant that grow well across the country. In the warm, humid South, snapdragons grow well in fall and spring. These plants may even grow through mild winters. In the North, where summers are mild, the snapdragon growing season may extend into early summer.
The flowers are native to Europe and the Mediterranean regions of the world. They were originally cultivated in southern Spain and spread to Italy and through there to the rest of Europe by the ancient Romans. Today snapdragon colonies may still be found growing in the ruins of ancient Roman temples in regions extending from southern France to Israel.
Snapdragon varieties are classified by size. The tallest snapdragons rise on stalks 2 to 3 feet tall. Intermediate-sized snapdragons range from 1 to 2 feet tall. Bedding types grow from 6 to 15 inches tall and rock garden hybrids grow no more than 6 inches tall. Flower colour may be red, orange-yellow or maroon. The stem hue varies with the flower colour. Dark-coloured flowers such as red flowers have dark green stems. Pale flowers such as yellow are borne on pale green stems.
Snapdragons grow best when they receive nighttime temperatures around 4.44 degrees C and daytime temperatures near 21.1 degrees C. The plants are extremely cold hardy. Once snapdragons harden off, they can withstand temperatures in the subfreezing ranges. Snapdragons must be well watered and mulched. When intense freezing temperatures arrive, the plants will pull all available moisture from the soil. During the coldest weather, gardeners may cover snapdragons with a layer of straw or pine needle straw to overwinter them. Once the weather improves, the beds may be uncovered again.
Plant snapdragons in mid-September in the northern regions and mid- to late October in southern regions of the country. Snapdragons will overwinter in mild climates and produce blossoms through the spring. Good companion plants for snapdragons include pansies, viola and ornamental kale.