I am looking for perennial yellow flowers for zone 2 (I know Toronto is zone 5) but I found it is better to have something can be hardy for zone 2 to be safe. height is 12-18 inch. (not Cone Flower). Any suggestion would be appreciate.
Ah! There are hardy chrysanthemums, developed in Manitoba where winters are far colder than ours in Toronto. Here are some options: Morden Cameo’ (creamy white), ‘Morden Canary’ (yellow), Suncatcher® (‘Jefsun’): bright yellow double flowers.
Call around to your local garden centres to see who carries them.
Without knowing the type of soil (sandy, clay, loam) you have or the amount of sunlight ( 2-4, 6-8) you receive it is difficult to give you a specific list. However, This link provides a list of other very hardy perennials which are not necessarily yellow in colour but will provide year round interest.