It's "garden phlox". Should be in full sun or mostly sun & give it room to spread. Don't toss it away, it's very pretty, especially when it spreads to a larger clump. Betty

looks more like a dianthus ("sweet william" or similar) to me. does it have a spicy fragrance similar to cloves? if so, that would be a trait common to this plant.
sun to partial shade.

Sure looks like a sweet william to me too.

sweet william

"I need to know so i can decide whether to transplant it to another bed or just pull it."
Nameing it should not be the criteria here. If it's pretty and you like it then keep it. If you don't like it then pull it, it's a weed.
I mow my vacant lot next door only twice a year, very early spring and very late fall in order for the pretty wildflowers that came up naturally to reseed themselves.

i respectfully disagree, ted.
if the plant is unknown to the gardener, it could possibly be an aggressive spreader. i think that is why she phrased her comment that way.
some plants can have attractive foliage or flowers and become garden pests; i.e. purple loosestrife, queen anne's lace, mexican petunia, chameleon plant, english ivy, etc.(all introduced species, by the way)
now, i know many folks cultivate the ones i listed but i don't because of their rampant habits.
if i had only known about those darn four-o-clocks and vinca major before i grew them. i am still pulling seedlings and runners after several years! :-)
the fact that she found this dianthus growing in an area where it may not have been planted warrants an inquiry but i don't know that it has a reputation as an invasive species. probably just a rogue seedling that found a suitable spot.

Jeff is right. I wanted to know because I already have 2-3 plants that I wish I hadn't or had known to be careful where I planted them. I have a small yard and invasive plants can take over quickly if I don't watch out.
Glad to know it is not an invasive flower, it IS pretty. Guess the birds helped me out on this one.

Definitely Sweet William. Mine are blooming now.

I purchased some Sweet William plants this year. Are they invasive? When will they bloom? They have been in the ground since early May and have lovely green foliage, but no flowers. Am I doing something wrong? My bed is in good shape (good soil, composte, etc.) They receive sun the first 7-8 hours of the day.

It does look like a type of dianthus. However the Sweet Williams (dianthus) I have in my garden do not make a cluster of blooms like this picture.

Lindy~I planted my Sweet Williams several years ago (maybe 5 yrs) and they have bloomed nearly all year long for that whole length of time. They are starting to die off now. They seem to be very hardy here in central AL.

Lindy~I should add that mine have not been invasive at all.

Don't worry that they aren't blooming yet. If they don't bloom soon, just wait and I'll bet they will when the weather starts to cool off in the fall.

If they do like mine have, you are likely to have flowers well into winter.

Sounds like you have them in a good place, mine seem to like lots of sun.

imadabble - thanks so much I was so concerned that they had not bloomed yet. It is nice to know that they eventually will. My mother always loved them and I guess I wanted to try to put something to remember her by in my garden. Thanks for your reply. Happy Gardening! :o)