Product thumnails in product listing on sidebar widget is too large.

I want to have a product list in my sidebar. When setting up the product listing widget, i check the thumbnail setting and have tried multiple sizes. Always, it is displayed as a full sidebar size and not a thumbnail size. Can you please help me figure out how to make it an actual thumbnail size?
Here is website address: http://hydrangea.oregoncoastalflowers.com/