How Many of These Thistle Seeds Will Sprout in Anderson Yards and Gardens Next Spring?

This field is east of Office Depot just off Scatterfield Road and 38th Street. Its thistle blooms are a flashy violet right now, and pretty to view from a distance. These thistle blooms attract butterflies and bees, but thistles are an invasive weed. Some states have laws requiring property owners to remove certain thistles before they go to seed.


There are a few dozen species of thistles. Some thistles grow to less than a foot in height, but thistles, like these in this field (either bull thistle or Canada thistle is my guess), grow to six feet.

Kings County, Washington published an article recently listing some of the characteristics of some thistles.

  • Originally from parts of Europe and Asia, this Class A noxious weed is now invasive in North America, South Africa, Australia, and New Zealand, among other places…
  • But once thistle shows up, it’s persistent. Seeds survive in soil an average of 16 years. One King County landowner eradicated a few plants from his pasture more than a decade ago. Last summer, he cleared a blackberry patch on the land. Earlier this spring, Weed Specialist Dan Sorensen found over 50 new plants growing in the cleared area!
  • One thistle can produce over 6,000 large seeds.
  • Milk thistle, another invasive species, is widely known as a medicinal plant, especially for liver problems.

Chris Hope in Permaculture Magazine, a British publication, expounds on the more positive uses of thistle.

  • One of the great things about thistles is that every single species is edible, so this is great news for foraging beginners! Even the closest lookalikes…are edible – (which includes the sow thistles and sea holly…
  • (As to eating thistle weeds, Hope says) …plants that have spines to offer protection against predators, have no real need for bitterness.
  • (Compared to our other vegetables commonly grown for the table) Weight for weight, thistles come out higher in fiber, protein, phosphorus, magnesium, calcium, copper, zinc, and other nutrients.

Yes, Indiana does have laws that order destruction of (one specific species of) thistle–Canadian thistle. Purdue Extension Publication FNR-436-W explains.

  • In the state of Indiana it is unlawful [IC 15-16-8, “Destruction of Detrimental Plants” law] to let Canada thistle reach maturity or bloom. This law was written in order to reduce the spread of Canada thistle in Indiana. At the very least any method that inhibits or stops flowering complies with the law. This can be achieved by mowing, tillage or herbicides. Mowing or the use of herbicides to control noxious weeds is allowed for CRP acreage at any time within the first three years of establishment, or prior to a Final Status Review, whichever comes first. Because Canada thistle is covered by Indiana law, CRP policy mandates that Canada thistle must be controlled.

MY QUESTION IS: Why are retailers in Indiana permitted to sell thistle seed as bird feed?



  1. What is sold as thistle seed is actually Niger..
    A self sowing annual that has the tiny seeds that finches live… also called “love in a mist”. Have no ide why it is called thistle seed unless it looks like it

    1. Nice to read your comment, Nancy, but that info seems dubious in light of observing my bird seed of six years ago being widely scattered by birds, other than finches, sparrows, blackbirds, etc. that tossed the thistle seed away, seed which has since propagated hundreds of thistles in my yard, gardens, alley and neighbors properties. Nyjer, or Niger, seed is another term for thistle seed and not a harmless seed from a different weed. By the way, thistle is a form of and relative to sunflowers.

  2. Field thistle or pasture thistle is common in indiana and not invasive though. Extremely beneficial to our wildlife and native to indiana. They look very similar to invasive thistle but field thistle is hairy on the underside of the leaves. Unfortunately it’s often killed because it is so similar and hurts our beautiful butterflies and birds. Please make sure to know what you are killing as it may be a beneficial plant.

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