Do you have a photo? I have never found these to self seed easily....though you are in a slightly warmer zone. Rarely do I find any seedling of these, and the in the rare occasion it is usually up late and doesn't get as big as a transplant would have. Years ago when I worked in a commercial nursery the seedlings of these were always a little delicate.....requiring good warmth to do well. Well enjoy them!

WN. Just kinda blown away. Seeds are well...itty bitty. We're talking 2 growing seasons later and it's still finding its way to sprout. I might even have had more last year, I was pulling all the seedbank Vinca from all sorts of places. I can easily spot 30+ various germinations here and there.

The kicker was the one in the OP. Did not see this in my daily inspections, and one day I walk up and I knew from a distance it was a vinca that seeded and it's almost a foot high, single stem (I think , will need reverify) with a single bloom on it. Go figure...I can easily say there must be at least 5 inches of -compost/mulch- ontop of it from it's original planting height. Unless I -brought- the seed up when planting new stuff or when the bulbs bloomed in the spring and -pushed- it up to the surface. Just can't believe 24 months later, they're still around...

Could you post a picture?

More germination continues. Last year, which would have been the following year since it was planted as a annual, I was pulling up every instance of germination that cropped up. As of today, there are a few intermingled in between this years current dense annual bedding area that are a full stem with blooms

By the bluestone walkway, there is like a row of small germinated leaves...a easy 20 there.

Riddles the mind for is just the simple fact, 24 months later, between snow, WIND, rain, compost, mulch, more wind, etc....seeds are still here and germinating to boot.

Amazing! Possible to post a photo??

Off topic , as I think of my fall overseeding on the hellstrip. If only I could get the grass seed to be so vigorous in -all climates-