Saturday Seed Co. seeds are suitable for growing in Zone 5 through to zone 9.
Click here for a link to a very handy chart for Southern Ontario of what to plant when. It's from West Coast Seeds. It's a PDF so you can easily print it.
Click here for chart for Central Ontario.
For everywhere else in Canada please have a look at THIS document to find out what zone you're in or inquire at your local nursery for start times.