Best plants to attract butterflies

What are the best plants to attract butterflies to my tiny, south-facing balcony garden in downtown Toronto. I have been growing herbs and vegetables in containers and would also like to have plants to attract butterflies?

Goldenrod

I have been developing a pollinator garden on top of our septic field-disturbed soil, mostly sandy, drains quickly as this field was created on a steep slope. Goldenrod is really coming along and is also filling in along edge of…