I am looking for flower seeds can grow in the shade, such as Polka-Dot Plant, Hosta etc. please provide advice for different flowers and how and where I can buy,
Below you will find a link to a Guide for Annuals for Shady Gardens written by the Toronto Master Gardeners.
Here is also the guide for Shady Perennials.
For supplier of good quality seeds, seedlings, potted plants for outdoors or tropical indoor plants, I would suggest you contact your local nursery or go to the Landscape Ontario website and ask for recommendations, see link below: