R1 usually refers to first-generation offspring created using a reversed female plant, sometimes described as a reversal cross. In cannabis breeding, this means a selected female is reversed to produce pollen, which is then used to fertilise another female plant. This method is commonly used in feminised seed production and allows breeders to combine or preserve desirable traits without using a male plant.

For growers, the R1 label gives useful insight into how a strain’s seeds were produced and why the resulting plants may carry certain traits. R1 genetics are often valued for their connection to carefully selected female parents, with breeders using reversal breeding to capture qualities such as terpene profile, potency, resin production, plant structure, flowering time, or colour. This category is useful for growers interested in feminised breeding methods, lineage detail, and cannabis seeds with a more technical breeding background.