Why link to your company's page? If you already have a good rating, then you will want to give your customers (and potential customers) an opportunity to view these ratings from an independent source. Additionally, you will want to encourage your customers to input their own experiences with your company into the Watchdog.
There are several ways to link to Cold Hardy Cactus's entry in the Watchdog. Here are some examples of HTML code you can use, as well as some graphical buttons that you are free to use.
The text link:
<a href="https://davesgarden.com/products/gwd/c/7416/">Click here to view Cold Hardy Cactus's rating with the Garden Watchdog!</a>