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.
Perennials for Shade in Dry or Moist Areas: A Toronto Master Gardeners Guide
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: