The weed you have sent the picture of is called Common mullein, Verbascum thapsus L. from the snapdragon family (Scrophulariaceae).
It is a common weed in Ontario showing up mostly in dry areas such as road sides and pastures. This weed is a biennial meaning it has a two year life span. The first year it is a rosette of soft hairy pale green leaves close to the ground. In the second year it shoots up the flowering spike and goes to seed. The plant has a thick sturdy tap root similar to a dandelion.
The most effective method of removal is to pull it out with as much of the tap root as possible so it does not grow back. Removing the plant before it goes to seed will decrease the risk of more plants showing up in your garden in the future.
Here are some web sites with further information: