Can Snapdragons Turn into Weeds?

Snapdragons (Antirrhinum majus) are used as borders for garden beds and as cut flowers. The plants are grown for their five-lobed flowers that are divided into a lower an upper jaw and available in a variety of colors. Although often grown as annuals, snapdragons are perennials in U.S. Department of Agriculture (USDA) plant hardiness zones 5 though 10. They are propagated from seeds and may reseed, but they are not considered weeds and are not invasive. A look-alike plant, wild snapdragon or yellow toadflax (Linaria vulgaris), however, is invasive.

Weeds are simply plants growing where they are not wanted, and they include plants with the potential to become invasive and quickly take over a garden or flowerbed. Weeds rob desired plants of necessary water and nutrients. Whether or not a plant is considered a weed depends on where it grows and how quickly it spreads. Wild snapdragon is considered a weed when it grows in an unintended area and because it spreads rapidly by both seed and creeping roots.

Because snapdragons are not weedy or invasive, you can contain them in a specific location without worrying they will invade other areas of the garden. Snapdragons are the backbone of many ornamental gardens and need a cool climate to thrive; the plants languish when temperatures remain hot for an extended time. Snapdragon seeds need a soil temperature of 65 to 70 degrees Fahrenheit to germinate. Besides propagation by seeds, snapdragons can be propagated from tip cuttings taken in summer.

Wild snapdragons can become weeds when they invade areas where they are not wanted. The invasive plants are perennials in USDA zones 4 though 9 and produce brightly colored blooms that look similar to small spurred snapdragons. The simple-to-grow plants' flower colors range from orange and violet to maroon and gold. Wild snapdragons are effective in rock gardens and for growing between paving stones. They also can be grown in other areas where their rapid increase in numbers is not a problem.

Wild snapdragons growing in unintended areas can be controlled. Control methods include pulling up and digging up the unwanted plants, removing as much of their roots as possible. This method can take several years to clear an area of wild snapdragons. Because wild snapdragons spread via their creeping roots, mowing is not an effective control for these plants.