Tall Thistle Plants (Cirsium altissimum) Quick Facts:
Host plant to Swamp Metalmarks and Painted Ladies
Nectar plant to Monarchs, Swallowtails, and many butterflies
Native to central, eastern, and southern US
Hardy in USDA zones 3-9
Full to partial sun
Moist to medium moist soil
Pinkish Purple flowers bloom late summer, usually in 2nd year
4-5 feet tall (sometimes much taller)
Space plants 18-24 inches apart
Not aggressive like non-native thistles
Thistle Please Your Butterflies
Imagine counting how many times a specific butterfly visits each kind of flower! Scientists have performed exactly these kinds of studies, and have determined that thistles are a preferred nectar source for many butterflies. In particular, they determined that Monarchs in the study paid about 51% of all floral visits to the regal purple blooms of the Tall Thistle. Thistles have been designated as a “high value nectar plant,” very probably because of the relatively high carbohydrate content of thistle nectar.
Black Swallowtails, Cabbage Whites, Chalcedon Checkerspots, Cloudless Sulphurs, Milbert’s Tortoiseshells, and Painted Ladies are among the butterflies who sip Tall Thistle nectar. Swamp Metalmarks and Painted Ladies are known to use the plant as a host. A fairly recent (Takahashi, 2006) survey done in Nebraska discovered that the Tall Thistle feeds at least 74 different types of insects!
Why Buy this Biennial?
The Tall Thistle grows a low-to-the-ground leaf rosette in its first year. Its namesake tall stems emerge with crowning large purple flowers late in the summer of its second year, after which it almost always dies. So where is the value of this plant?
First, its large (up to two inches across) blossoms last from 4-6 weeks, and their late-season bloom schedule makes them utterly invaluable to Monarchs as they migrate to Mexico for the winter. Each individual plant produces 25-45 flowerheads–quite the eye-catching display! And as mentioned before, these blossoms are chock-full of pollinator-popular premium nectar.
Although the Tall Thistle is not aggressive, its many flowers make for successful self-seeding. Your beautiful pinkish-purple nectar cups have the ability to reseed and continue their butterfly nourishment! Tall Thistle seeds are much beloved by goldfinches–they eat as many seeds as they can gobble and use the down surrounding the seeds to line their nests.
if you have sensitive skin, take note: Tall Thistle is the least prickly of all thistles. Most hands can handle it without gloves!
Non-native thistles, which tend to spread invasively by rhizomes, have given the whole thistle family a very bad reputation. North American native thistles, however, are highly desirable–both for their value to pollinators and well-behaved growing habits. Planting native thistles (such as the Tall Thistle) can help curb the onslaught of non-natives. The insects that eat thistles actually cause more damage to the invasive non-native plants. The Tall Thistle grows naturally in overgrazed pastures and degraded prairies, helping to save these areas from becoming barren wasteland. It prefers moist but well-drained soils. The sunnier the site, the taller the thistle.
You can always trust Joyful Butterfly to provide only those plants which are beneficial and safe for our pollinators.