It's a volunteer in my neighbors balcony pot. It survives winters.
Floral, I wouldn't rule out Boltonia asteroides just yet. Clearer photos of the flowers and phyllaries should confirm whether this plant is Boltonia asteroides, Symphyotrichum pilosum, or Symphyotrichum dumosum. I looked at the gestalt of the plant, and thought Symphyotrichum. Boltonia asteroides normally has larger leaves, sparingly distributed throughout the flowering branches, also the flowers look smaller than B. asteroides, and the ray petal count seems less than normal. I grow Boltonia decurrens and Symphyotrichum pilosum. Boltonia species have more ray petals than Symphyotrichum species, same as Erigeron species.
Photo by Katy Chayka, (Minnesota Wildflowers.)
Boltonia asteroides. The person who took this photo was hoping this plant was Solidago ptarmicoides, but S. ptarmicoides leaves are much narrower than these. I was stumped, and I ruled out Boltonia because of this plants small stature. My Boltonia decurrens has reached 11 ft. tall, and I have no experience with Boltonia species in the wild. We had a long drought and it must have stunted this plant and caused it to flower without forming large branches.
Beauty is in the eye of the beholder. Around my area the Frost Aster is common in the wild, and a common wind planted garden vollunteer. We don't recommend growing it in the garden because of it's weediness, but I still appreciate it's flowers at a time of the year when most other plants have finished blooming. A pot with an aster is better than a pot with nothing but dirt. Several asters I grow have that weedy nature, but I leave many vollunteers to bloom for the pollinators and migrating Monarch butterflies, and then I pull them out afterwards so they don't go to seed. In a fake world of asphalt and cement, a bee or butterfly gathering nectar on a plant that vollunteered in a vacant pot can give hope, peace, and enjoyment. It could be a life saver for an exhausted migrating Monarch butterfly? Enough of the negative branding, cancel culture complainers who just love to criticize. They lack understanding and would rather comply with, and spread the weed propaganda the herbicide corporations have been poisoning American's minds with for years.