Feelings: Sleepy .Relaxed .Hungry Negatives: Dry mouth .Dry eyes .Dizzy Helps with: Stress .Anxiety .Pain calming energizing Granddaddy Purple effects are mostly calming. low THC high THC Granddaddy Purple potency is higher THC than average. Granddaddy Purple is an indica marijuana strain that goes by many different names, including "Grand Daddy Purp," "Granddaddy Purps," "GDP," and "Grandaddy Purple Kush." Popularized in 2003 by Ken Estes, Granddaddy Purple (or GDP) is a famous indica cross of Mendo Purps, Skunk, and Afghanistan. Other people claim it is Big Bud x Purple Urkle. Either way, this California staple inherits a complex grape and berry aroma from its Purps and Ghani heritage.