These were started from seed about two years ago. After admiring a neighbor's plants, I was later given some seeds from them. They were planted and nothing grew that year. So, some seeds were purchased form the store and planted the following year. About four plants survived infancy, and the rest of the seed packet was thrown out. These resulting plants lived through the summer and never bloomed or grew much.
All that changed the following year (last year), when they came up after the spring and bloomed, then started spreading throughout the summer. This is the second year of blossoms, and the plants are very healthy and happy from the looks of the abundant flowers. I will need to thin them out now, probably in time for the neighborhood Fall Plant Swap Brunch.