Tall Blue Lettuce Lactuca biennis

Tall blue lettuce is a native biennial (sometimes annual) herb in the daisy family (Asteraceae) found in most of North America, including North Carolina, in moist woods and thickets and along stream banks.. The genus Lactuca comes from the Latin lac, for the milky juice of the stem and root. The species, biennis, refers to the plant being biennial.

Tall blue lettuce can grow up to 10 feet tall but is usually 5 to 6 feet and 1 to 2 feet wide. It prefers moist soil and partial to dappled shade. It prefers a loamy, moist, well-drained soil. Keep the soil moist but not waterlogged. Propagation is by seeds.

The tall stem produces narrow clusters of small light blue to whitish ray flowers but no disc flowers in July to September. The leaves are variable with the basal rosette leaves being winged and deeply, pinnately lobed. The leaves are smaller and sessile as they go up the stem. Even though it is called a lettuce, it is not edible. Native bees nest in the dead, hollow stems, so gardeners are encouraged to cut back dead stems to 12 to 24 inches and allow them to remain standing until they disintegrate on their own. Read more about best practices for stem-nesting bees in this NC Extension publication.

This plant is not widely cultivated but could be used in a woodland garden, along a stream or pond or a shady naturalized area. It is beneficial to wildlife.

Insects, Diseases, and Other Plant Problems:  Watch for aphids, spider mites, leaf miners, snails and slugs, scale and fungus gnats, Watch for downy mildew, powdery mildew, leaf spot diseases and lettuce mosaic virus.