America Nursery and Landscape Association
www.anla.org
National organization for the nursery and landscape industry.

American Society of Landscape Architects
www.asla.org
National professional association of landscape architects.

Associated Landscape Contractors of America
http://www.landcarenetwork.org/cms/home.html" target="-blank"
National organization for landscape contractors.

University of Illinois’ Landscape and Human Health Laboratory
http://lhhl.illinois.edu/

Project EverGreen
www.projectevergreen.com
Information about the positive effects of well-maintained green spaces, including lawns and landscapes, sports turf, golf courses and parks.

Exotic Pests
http://www.ceris.purdue.edu/napis/

Fire-Safe Landscaping
http://www.usfa.dhs.gov/citizens/all_citizens/home_fire_prev/rural/landscape.shtm

Invasive Species
www.invasivespecies.gov/

Mulching Trees Properly http://www.gardening.cornell.edu/factsheets/mulch/toomuch.html

Hardiness Zone Map, U.S.
http://www.usna.usda.gov/Hardzone/index.html

Integrated Pest Management (IPM) Resources
http://www.ipmnet.org/

Poisonous Plants  
www.ansci.cornell.edu/plants/index.html

Sustainable Landscapes
http://www.ag.udel.edu/udbg/sl/

Project for Public Spaces
www.pps.org
Dedicated to creating & sustaining public places that build communities.