Heat Units for Growing Herbs

We are looking into growing herbs commercially. Is it important to consider the heat unit requirement for different herbs. We are moving to Durham, Ontario and aren't sure which herbs will do well with less heat units. Corn and soybeans are rated according to the heat units required. Are herbs the same? And if so, do you have this information?

As far as we know, no one has done the research to measure or estimate the heat unit requirements for herb crops. It would be very useful to have such ratings, though.
The heat unit rating is probably more critical for the annual crops. For the biennial and perennial herbs we have zone ratings which are largely based on minimum winter temperatures. They can be used as a guide to which of these latter herbs can be grown in your area.
The hardiness zone ratings for every Richters biennial or perennial herb are available on our website. Go to www.richters.com and then to the Richters Infobase area.
Along with the hardiness ratings, the main way by which to decide if a crop with do in your area is to ask other local growers what works and what doesn't. If you are unsure about any particular crop, feel free to contact Richters for advice.