What are the medicinal herbs more in demand in Canada and USA thatt 
could be cultivated hydropony

Hello camilosky, Here is a list and link for the top 10 medicinal herbs:

http://www.pharmacy.arizona.edu/centers/apdic/popular.shtml

10 Most Popular Medicinal Herbs
Echinacea, Ginger, 
Ephedra, Ginseng, 
Feverfew, Saw Palmetto, 
Garlic, St. John's Wort, 
Ginkgo Biloba, Valerian

Here is a list and link to a hydroponic medicinal herb growing kit:

http://www.herbkits.com/hydroponickits.htm

Chamomile      Mint      Calendula      St. John's Wort     
Dill      Lavender      Lemon Balm      Feverfew
Yarrow      Fennel      Echinacea      Horehound    

I could not find a list of all medicinal herbs that can be grown using
hydroponics. However, I called the National Sustainable Agriculture
Information Service (contact info below) and talked with Preston. It
is his opinion that any medicinal herb can be grown using hydroponics.
He was very helpful and said that their real expert is Steve. Steve
was out of the office, but I am sure that he would be a good guy to
talk to.

National Sustainable Agriculture Information Service
http://attra.ncat.org/index.html

(800)346-9140

Good luck with your growing,
Redhoss

Thanks for the information. It will help me to get started.

If you are also looking for indoor gardening information on growing
herbs using hydroponics you should check out Advanced Nutrients Direct
at: www.advancednutrientsdirect.com