Posted: 11/04/2015 at 06:52
Information on most plants is easily available online - just put it into Google and choose the most appropriate source of information.
You can always narrow your search by using specific search terms e.g. "salvia amistad hardy?" comes up with the Hayloft site with lots of cultural information including that it is not reliably hardy below -5C http://www.hayloft-plants.co.uk/Salvia/Amistad-1-young-plant/prod5023.html
I frequently use my iPhone at the garden centre to find just such information.
You don't need the A-Z Encyclopedia of Garden Plants to be available online to get the information you need.