HP 21 is a modern hybrid strain derived from the breeding of U Dub and HP Bx. This genetic pairing results in a versatile plant suitable for cultivation in both indoor and outdoor environments. Growers can expect a high yield from this variety, which reaches maturity after a 63-day flowering period and requires a moderate level of technical skill to successfully cultivate.

The chemical profile of HP 21 is defined by a complex terpene arrangement, led by dominant myrcene, followed by limonene, caryophyllene, and beta-pinene. Further nuance is provided by linalool, pinene, bisabolol, camphene, nerolidol, guaiol, and ocimene. This diverse composition contributes to a distinct aromatic and sensory profile that reflects the interplay of these eleven specific constituents.

As a THC-dominant cultivar, HP 21 produces effects characterized by a sense of relaxation, happiness, and an uplifted mood. These properties make the strain a functional choice for those seeking relief from stress and physical pain, or assistance with sleep. The influence of the strain continues through its genetic legacy, most notably as the parent of the offspring known as Jane Doe Skunk.