Get to know your local thistle … How does thistle spread? Canada thistle does not do well when shaded, so maintaining a cover of desirable plant species will help suppress Canada thistle and prevent establishment. In fact, Canada thistle is older than Canada itself. Two years before confederation, legislation required farmers to cut the weed 1. Cirsium arvense buds and blossoms. Description. They ate anything, but by far, they preferred Nyjer. ) Canada thistle develops seed sparingly and may produce 1,000 to 1,500 seeds per flowering shoot. Canada thistle has long been one of the most problematic weeds in Iowa and the northern corn belt. Dense patches are formed where a single male or female plant has spread … Its deep roots are the real issue. Seed production is usually completed in early July. Seeds are viable in the soil for up to 20 years. For interest's sake, I found some Canada Thistle seed and placed it alongside Nyjer. is an invite-only member network and summit that brings together leaders, from the world’s most innovative companies, along with cultural icons for high level discussions on culture, media and marketing. An aggressive perennial with a vigorous root system that continually produces new shoots, invading new areas and outcompeting other vegetation types. Similar species: Canada thistle is distinguished from all other thistles by creeping lateral roots, dense clonal growth; and small dioecious flower heads (meaning male and female flowers are produced on separate plants). Unlike other thistles, the Canada thistle has a deep and wide-spreading root system. However, it is difficult to distinguish the two flower types based on appearance. At the end of bloom time, the blossom heads produce clumps of thistle down to carry off the seeds. Unlike the non-native thistles, many of the native thistles have become uncommon in the landscape. Give it an inch or two of bare ground near your Joe Pye Weed, and it will fill it in eagerly, and also kill your Joe Pye Weed in the process. https://bcinvasives.ca/invasive-species/identify/invasive-plants/canada-thistle While modern herbicides have greatly reduced problems caused by Canada thistle in crop fields, it is still a formidable foe in pastures, roadsides and other less intensely managed areas. Canada thistle is native to Europe. Birds pictured: One Pine Siskin and two American Goldfinches, a heap of Common Redpolls (We fed about 70 of these birds for a month in 2013. A common type of weed most homeowners and gardeners hate to see sprouting up on their turf is thistle. Field thistle does not spread by underground stems (rhizomes) or roots and is not invasive or as difficult to control as non-native thistles. It was introduced to North America in the 1600s, probably in agricultural seed shipments and is now widespread throughout the United States and Canada. A tough weed to kill, the flower heads on thistles possess thousands upon thousands of thistle seeds, which allows them to spread at an exponential rate both above and below the soil. Their perfume is quite beautiful. The Canada thistle commonly grows in clumps of plants, because it will spread by runners. In Indiana, Canada thistle normally initiates growth in spring, reaches the flower-bud stage the first week in June, and full flower about the third week of June. PTTOW! Blossoms are a light pink-purple, with many blossoms per plant. Revegetate disturbed areas immediately. The seeds of this broadleaf perennial can go dormant for up to 20 years 2, but only about 10% of Canada thistle is spread through seed 1. Canada thistle is a cool season perennial which spreads by seed and vegetatively by creeping roots. 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