American Hemerocallis Society
http://www.daylilies.org
The daylily (the latin name for the daylily plant genus is hemerocallis) has evolved to the point where it is one of the most exciting and popular plant varieties used by home and commercial gardeners.
ANLA (American Nursery & Landscape Association)
http://www.anla.org/
Now in its 128th year, the American Nursery & Landscape Association is the national voice of the nursery and landscape industry.
Canada Hardiness Zones
http://sis.agr.gc.ca/cansis/nsdb/climate/hardiness/intro.html
The Plant Hardiness Zones map outlines the different zones in Canada where various types of trees, shrubs and flowers will most likely survive. It is based on the average climatic conditions of each area.
European Hardiness Zones
http://www.uk.gardenweb.com/forums/zones/hze.html
Perennial Plant Association
http://www.perennialplant.org/
A professional trade association dedicated to improving the perennial plant industry by providing education to enhance the production, promotion and utilization of perennial plants.
The American Horticultural Society
http://www.ahs.org
The American Horticultural Society (AHS) is one of
the oldest national gardening organizations in the country. Since 1922, we have provided America's gardeners with the highest quality gardening and horticultural education possible.
US Hardiness Zones
http://www.usna.usda.gov/Hardzone/ushzmap.html
Use this interactive site to determine your hardiness zone.
USA Freeze/Frost Maps
http://www.ncdc.noaa.gov/oa/documentlibrary/freezefrost/frostfreemaps.html
