Ageratum is an attractive, flowering annual plant that is rarely damaged by deer. The creatures prefer to pass by this plant and instead munch on vegetables and other flowers. Though gardeners in deer-prone areas often select ageratum because it is one of the most effective deer repellent plants, this annual is also very beautiful.
The fluffy, blue flowers that grow on an ageratum look pretty when cut and displayed in a vase. Though blue is the most common color, white, lilac, and pink can also be found. The plant grows to about six to eight inches tall in small hills and its leaves are usually oval and hairy, forming compact clusters. Taller versions grow to about 18 inches.
Many gardeners use this plant in their beddings, as a border, or in a rock or container garden. These deer resistant plants grow well in partial shade or full sun when placed nine to twelve inches apart. Growth season begins in early summer and runs through the first frost. The plant is easy to grow, making an excellent choice for a beginner garden.
When ageratum is grown outside of a natural range, it can become an environmental weed. Gardeners with children should be cautious because several species of this plant are toxic due to their pyrrolizidine alkaloid content. Liver lesions and tumors may be caused by ageratum conyzoides and ageratum houstonianum. The ageratum seed is poisonous if it is ingested and handling the plant may result in an allergic reaction or skin irritation.
Blooms will begin appearing in late summer and the fragrant flowers attract birds, butterflies, and bees. Since this plant self-sows, it should be deadheaded if volunteer seedlings are not desired next season. To collect the seeds, first allow them to dry on the plant and then remove them to plant in other areas next year.