I am a novice in growing Dahlia and would love to meet an experienced grower in the Durham region of toronto that would be willing to teach me how to grow Dahlia for shows.
Michael, check out this group on Facebook, and perhaps ask Martin the moderator privately if he has any suggestions on who you may contact. Don't know how close he is to you (Canada is a big place), but he has good grower contacts in that area and believes in the importance of mentorship.
This group has a wealth of documents worth checking out under the 'files' tab, and many hybridizers and advanced show folk read what is posted. Their response to questions depends on how specific the questions are, and how much someone has done their homework first before asking. (Rule of thumb on that forum is-" don't ask if the answer is a google search away.")
Cheers, and good luck at the shows!
Here is a link that might be useful: Growing and Showing Dahlias