Buy High School Sweetheart Cannabis Online. High School Sweetheart is an evenly balanced Hybrid – 50% Sativa and 50% Indica. This strain was originally bred by Gage Green Genetics, this strain is a cross between Cherry Pie Kush and Grateful Breath. With THC levels ranging from 15-23%, this is a surprisingly mellow smoke and can be enjoyed any time of day. With earthy undertones and a sweet berry finish, we can see why this strain is so popular!