Accept it for what it is. A mistake based upon a presumption. If the plants are not in your formula for your garden remove them and give them to someone else or dump them.
As for a nursery that specializes in natives-this in no way means that they are not selling other kinds of plants-only nurseries that state that they sell natives only or exclusively natives. But
the real problem is knowing what natives are. You really need to do your homework on what native plants you want for your garden and you can easily research this on the net. Do this before visiting any nursery as native plants can be found at many if not most nurseries. Just know what you are looking for before buying and do not buy on impulse.
In a way of speaking: Dianthus is a native species, somewhere a native species! Just not locally so!!

Here is a link that might be useful: NY natives

Hello, thanks for the response. As I said I usually do my research first and then buy. This was an impulse buy and by the way this nursery calls itself "a Native Plant Garden Center". I really thought it was safe to assume that they only sell native plants. But I know what they say about "assume" - I guess I learned the hard way. Caveat Emptor.

Yep, just a mistake, but with dianthus it doesn't seem like a bad one. I'd enjoy them this year and then decide next year (or the next) what to do. I have given away plants once I decided I didn't want them (for whatever reason). People are usually happy to get them and sometimes you can get them to trade you something native in return!

Next time you go to that nursery you can determine if they are "mostly" native or if they really meant to be all native but made the mistake themselves.

I wrote what I hope is a polite email inquiring about it. I hope that they will respond. Thank you.

I know how you feel I've done that many times. As far as dianthus cheddar pinks go I had a similiar experience several years ago at an annual native plant sale to raise money for a local landmark. I bought what I thought was a native silene. When I came home and looked it up I found out it was a European silene. Ah well live and learn. It didn't survive anyway.

Some places even label some plants as "native" that are not. If I remember correctly, there are also some plants that have subtypes that are native as well as subtypes that are not and some that have cross-bred (maybe phragmites?). I have found very few sources that sell native plants exclusively. If the particular plants you bought are not invasive you could probably leave them be until you purchase replacements.

You will find many people in the nursery and landscaping trades who use a very loose definition of 'native' or simply use the term without any knowledge of where a plant originates. Some people apparently use the term 'native' to mean 'wild strain' which is to say a plant that originates in Asia, but is being sold in a wild form, not a cultivar or hybrid, would be called 'native.' Another interpretation of 'native' is the same as 'wild;' if a plant grows int he wild, it is called native by some people (as in out 'native' orange daylily). These definitions are obviously not consistent with the way most of us in the gardening and naturalist communities use the term 'native' so it is important to do your own research and don't trust a person to know what is native just because that person is selling plants. I have had landscapers and nursery people vigorously argue that plants I know to originate in Europe and not occur naturally in North america are native. Another concern is mislabeled plants; it is very common to find mislabeled plants everywhere from giant home improvement stores to specialty nurseries to botanic garden plant sales. When a plant is large and blooming and you are familiar with the species, you might notice the error, but how can you be sure you are getting what you think you're getting when you buy a plant you are not familiar with? I guess one could take a plant key shopping, but none of us does, so we all get a few mislabeled plants from time to time. The main point, I guess, is to not be too confident that the plant you have is what the label read when you bought it, especially if the plant doesn't seem quite right.

Unless the Dianthus label said "North American Native Plant", I don't think you have a complaint. Very few nurseries sell only natives, even if they specialize in them.

Hi all, thanks for all the replies. I just wanted to tie up the loose ends and tell you that the nurseryman did reply, saying that 70 percent of their stock is native. It never crossed my mind that given their name, Native Landscaping, they would be selling anything but natives. anyway, thanks again.

Its kind of frustrating that of all the plants that they had there, you ended up picking out one of the 30% that wasn't native.

There is a small nursery here that specializes in natives, he advertises as "Native Illinois Plants". And when I overlooked his stock, I questioned him on several of his plant species. He will say, Oh yes, that one is not native to Illinois, but its native to the PNW and grows quite well here. So an unsuspecting customer, would not know to ask, and could easily think they bought a native illinois plant, based upon his advertising...

I don't fault them for selling non-natives, because a native only market is pretty limited. But I do think they should clearly mark which plants are native and which ones are not.