The American goldfinch loves to eat thistle seeds. Thistle seeds found at garden centers for birds are sterile and are not the invasive thistles that will take over gardens and lawns. (Submitted photo)

Q: I want to feed the goldfinches, but I don’t want thistles all over my yard. Is there a way to do this?

• Molly from Salem

A: Use the thistle seed that you find at the local garden center. This product is NOT the thistle you think it is. It is not a problem.

The invasive plant you are referring to is Canada thistle, Cirsium arvense, a native of Europe and Asia. Yes, it is a real pain if you get it in your garden. Once you get it, the plant is nearly impossible to control.

This is because of the shoots that seem to pop up out of nowhere. These shoots are the result of an extensive underground rhizome system of the plant. You can learn more about this bad plant and how to control it at http://go.osu.edu/Canadathistle.

Now, for the GOOD thistle seed.

The seed we feed the birds is the seed of the African yellow daisy, Guizotia abyssinica. Nyjer is grown in Africa, particularly Nigeria, which is probably the origin of our name for the seed, and India. The seed is sterilized by intense heat to prevent germination of any seeds. This is required to prevent the introduction of invasive plants.

It is believed that calling the seed thistle may have become popular because goldfinches, which adore Nyjer seed, also use the down form to line their nests.

The biggest problem with nyjer seed is the mess left by hulls on the ground under the feeder. The small black hulls can smother grass and other plants. While the ground-feeding birds appreciate this spilled seed, you probably won’t.

Using the correct feeder can help.

They come in two forms — tube feeders with very small feeding ports, and thistle “socks” — fine-mesh bags to which birds cling to extract the seeds.

The seed within thistle socks can become quite wet with rain, so only use large ones during periods when you have enough finches to consume the contents in a few days. Adding a platform beneath the feeder or choosing a feeder design with a wide base can minimize spilled hulls and loose seed.

It is an exceptional energy source for birds. It is about 30 percent fat and 20 percent protein, which makes it a good source of food for birds. Nyjer is a great seed to offer finches and other small seed-loving birds. So please feed these wonderful birds. Their favorite food is not the source of the problem.

For complete details on feeding the birds (and specific birds) this winter, go to http://go.osu.edu/bestbirdfeeding.

For more on bird ID and more, go to http://www.birds.cornell.edu.

Scudier is an Ohio State University Extension Master Gardener Volunteer in Mahoning County. The Plant and Pest Clinic is open for help with plant issues, soil testing and insect identification. Winter hours vary. During the off season, questions can be submitted at any time. For deetails, visit go.osu.edu/mahoningclinic or call 330-533-5538.