I live in Chicago and planted my pansies from seeds in April, in my air conditioned apartment. They get plenty of sun and look healthy. I have them in the south-facing windows. Now that the temperatures have gotten cooler, I was expecting them to start blossoming, but they haven't yet. Some of them are kind of tall and hang off the sides of the pot, which I am not sure is normal. I was wondering why they aren't blooming and when I should expect them to.
Why Haven’t My Indoor Pansies Bloomed?
Certified GKH Gardening Expert
It may be too much nitrogen. Try giving them a little bone meal. This will boost the phosphorus, which will help with blooming.
This article will cover some other issues that may cause plants not to bloom: