Do you need solid purple, or will reddish purple with a white edge do? I have grown plenty from seed and they are very easy but it took me two winters to get blooms and it was a seed mix so I had to wait all that time to weed out the colors I didn't want. Or are you talking about the short pale lavender dianthus? I grew that from seed too.

I didn't collect seed this year and I didn't write down which pot bloomed which color, but they will bloom again next spring/early summer and I have plenty to share. I was growing them for the darker red with white edges so I weeded out the solid colors - oops.