General

• Denver Botanic Gardens
  
• CSU Cooperative Extension
  
• Center for Invasive Plant Management
• Plant Select
• Gardening With Wildlife
• CSU Estension Wildlife Master Program
  

Garden Plants

• DenverPlants.com
• High Country Gardens
• Niche Gardens
• White Flower Farm
• Wayside Gardens
• The Lily Garden
• Colorado Native Plant Society

Roses

• High Country Roses
  Weeks Roses
• Jackson and Perkins
• Witherspoon Rose Culture
• Nor'East Miniature Roses Inc.

Seeds

• Antique Flowers Select Seeds
• Western Native Seeds
• Park Seed
• Prairie Frontier
• Wildseed Farms
• Applewood Seed Co.
• Burpee Seed Co.
• Johnny's Selected Seeds

Water Gardening

• Paradise Water Garden
• Lilypon Water Garden
• Tricker's Water Garden Catalog
• Pond Filtration
  

Gardening Tools and Gifts

• Smith and Hawken
• Henri Studio Inc.
• Gardens Green
• Lee Valley

Lighting

• Escort Lighting
• Nightscaping

Xeriscape / Drought

• US Drought Monitor
• Associated Landscape Contractors of Colorado
• The Green Industries of Colorado
• Xeriscape Colorado, Inc.
• Cheyenne Mountain Zoo Xeriscape Garden