Canada Thistle is an upright herbaceous perennial weed in the Asteraceae (daisy) family. It is native to Europe, Asia, and Africa where it is found in wet meadows, swamps, bogs, and moist woodlands. It was introduced to the United States in the 1600's and is considered a noxious weed in 43 states including North Carolina. It is found in most of the US and southern Canada. Stems are upright up to 6' tall, grooved, and just a few hairs or none. The stems are also slender and branched only at the top. The leaves are poky like other thistles and it has purple pink flowers that appear in the summer. Canada thistle has male and female flowers on separate plants, but the flowers look similar to each other. Male flowers will not produce seeds, female flowers are fragrant. It prefers moist soil, sun to partial shade but withstands a variety of soil conditions and is most commonly found in disturbed areas, clearings or agricultural sites. Canada thistle spreads through both seeds and budding from underground roots. The common name Creeping thistle comes from its tendency to spread by lateral root growth, or its seeds are wind dispersed allowing it to rapidly form dense stands that can shade out native plants. Its root system can extend more than fifteen feet out and six feet down from the plant, making management difficult as new plants come up from the roots. Thistles are a great option in your meadow garden or naturalized area when looking for a plant to attract pollinators and seed-eating birds. However, it is considered a noxious weed in North Carolina and in many areas of the United States. Please consider planting the Native Alternative Plants shown in the left sidebar. Canada thistle should not be introduced into the garden. Insects, Diseases, and Other Plant Problems: Canada thistles extensive and aggressive root and shoot system coupled with its prolific seed production make it very difficult to manage. Consistent repeated mowing and/or hand pulling can deplete the root system storage over a series of years. Biological and chemical management may need to be used in conjunction with mechanical measures.
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.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; High Organic Matter; Loam (Silt); Sand
Soil pH
Alkaline (>8.0); Neutral (6.0-8.0)
Soil drainage
Moist | Occasionally Dry | Occasionally Wet | Very Dry
Available space
12 inches-3 feet
NC region
Mountains
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous
Form & Appearance
Habit / form
Erect
Texture
Coarse
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate; Rosulate
Leaf shape
Elliptical; Lanceolate; Oblong
Leaf margin
Lobed
Leaf feel
Prickly
Leaf size
3-6 inches long, 1-3 inches wide
Hairs present
Yes
Leaf detail
Dark green, deeply lobed, elliptic to oblong-lanceolate leaves 2"-6" long (5"-8" basal leaves) sometimes slightly clasping the stems; tomentose below and very prickly.
Flower color
Pink; Purple/Lavender; White
Flower value
Fragrant
Flower form
Head
Flower shape
Dome
Flower size
< 1 inch
Flower detail
There are male and female plants. Female flowers have a scent and male flowers do not. Pink, deep lavender, or white flowers; bracts are tomentose without spines. Flowering occurs from June-August and an average flower produces 2000 seeds per plant.
Bloom time
Summer
Fruit color
Cream/Tan
Fruit type
Achene
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
Tiny dry 0.1" long with feathery white to light brown pappus
Stem color
Green
Stem detail
Slender, smooth, grooved stems that sometimes have short hairs. Stems do not have conspicuous spines.
Wildlife & Ecology
Native status
Non-native
Origin
Eurasia, Northwestern Africa
Distribution
Most of the US and southern Canada
Wildlife value
The seeds are rich in oil, an important food source for seed-eating birds.
Attracts
Songbirds
Food & Medicine
Harvest time
Fall
Fruit type
Achene
Uses (ethnobotany)
The feathery pappus from the fruits was used by the Cherokee as fletching on their blow darts.