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.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Dappled Sunlight (Shade through upper canopy all day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
High Organic Matter
Soil drainage
Good Drainage | Moist
Available space
3 feet-6 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 5 ft. 0 in. - 10 ft. 0 in. | Width: 1 ft. 0 in. - 2 ft. 0 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Erect
Texture
Coarse
Leaf color
Green
Leaf arrangement
Alternate; Rosulate
Leaf shape
Deltoid; Elliptical; Lanceolate
Leaf margin
Lobed; Serrate
Leaf value
Showy
Leaf size
> 6 inches long, > 6 inches wide
Hairs present
Yes
Leaf detail
The leaves vary with the basal larger leaves being winged, alternate, triangular and deeply pinnately lobed with serrated margins. They are up to 12 inches long and 8 inches wide. The leaves become smaller with fewer lobes as they ascend the stem and are lance-elliptic. They are dark green with lighter undersides and hairs along the veins of the undersides.
Flower color
Blue; Cream/Tan
Flower form
Panicle
Flower shape
Radial
Flower size
< 1 inch
Flower detail
Flowers occur in long, narrow panicles. The small individual flowers are 1/4 to 3/8 of an inch with several light blue to cream colored bisexual ray florets. The bracts are green and may be purple-tipped, overlapping and appressed.
Bloom time
Fall; Summer
Fruit type
Achene
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
Flattened, mottled brown seeds have a tan fluffy pappus attached for wind dispersal.
Stem color
Green; Purple/Lavender; Red/Burgundy
Stem detail
The stem has a milky sap when broken. It is branched near the top of the plant. They are ridged, green to reddish or with purple streaks. Sparse white hairs present.
Wildlife & Ecology
Native status
Native
Origin
Much of North America
Distribution
AK , CA , CO , CT , DC , DE , IA , ID , IL , IN , KY , MA , MD , ME , MI , MN , MT , NC , ND , NH , NJ , NY , OH , OR , PA , RI , SD , TN , UT , VA , VT , WA , WI , WV , WY Canada: AB , BC , MB , NB , NL , NS , ON , PE , QC , SK , YT
Wildlife value
Flowers attract pollinators. Host plant for the common looper moth and virgin tiger moth. Dead stems are used by stem-nesting bees.