Starting Business Growing Herbs in France

I'm living in France, where I would like to start my own business in aromatic plants and medical plants. The winters are really cold -18 degrees and summers +38 degrees. I would like to know which plants are the best for me to cultivate here in France.

Most perennial herbs do very well in this range of temperatures. Rainfall is also important for determining which crops might be most suitable. I also like to see which weeds are currently enjoying growth on the land, as that often is more accurate to soil types than any chemical analysis. Often what is growing there is what might want to be expanded (e.g. dandelion).
With today's competition and demands and surpluses, it is also important to think in terms of what cottage industry might want to be considered with your specific crop selections. This industry is no longer about raw materials, but what is produced from the farm itself (like soaps, herbal coffee, or other finished product).
I have written an article on this subject and this direction for markets at:
www.nwbotanicals.org/oak/altagri/nitche.htm