The term “pheno,” short for phenotype, describes the observable characteristics of an individual cannabis plant. Even when grown from seeds of the same strain, each plant can express a unique combination of traits, like its physical structure, aroma, and chemical profile. The phenotype is the reason why two plants with identical parentage might look, smell, and affect the user in completely different ways. Understanding this concept explains the variability found across harvests and why certain individual plants become highly valued by both breeders and consumers.
The Core Difference: Genotype Versus Phenotype
The foundation of a cannabis plant’s potential lies in its genotype, which is the fixed, inherited genetic code contained within the seed. This genotype is the complete instruction manual passed down from its parent plants and dictates the range of possibilities for the plant’s final form. In the context of cannabis, the strain name, such as ‘Blue Dream’ or ‘OG Kush,’ is essentially a reference to a specific genotype that carries the potential for certain traits.
The phenotype, in contrast, is the physical and chemical manifestation that results from the expression of that genotype. While the genotype provides the blueprint, the phenotype is the final constructed outcome, which can vary significantly even with the same set of plans. The genotype is stable and unchangeable throughout the life of the plant, whereas the phenotype is the dynamic expression that can be influenced by external factors.
Observable Characteristics Determined by Phenotype
One of the most significant aspects of a phenotype is its chemical profile, specifically the ratios of cannabinoids and the composition of terpenes. A single genotype can produce phenotypes that express drastically different concentrations of compounds like THC, CBD, or minor cannabinoids such as CBG. This chemical variation directly dictates the potency and the overall physiological effect experienced by the consumer, determining if the plant is considered a high-THC or a balanced variety.
The terpene profile, which governs the plant’s distinct flavor and aroma, is also highly dependent on the expressed phenotype. For instance, one phenotype may heavily express the citrus scent of limonene, while its sibling might lean toward the earthy notes of myrcene or the spicy aroma of caryophyllene. These aromatic compounds modulate the effects of the cannabinoids through what is often called the “entourage effect.”
Beyond the chemical output, the phenotype determines many observable physical characteristics relevant to cultivation. These include the plant’s overall height, branching structure, the density of the final flower buds, and the time required for flowering. Phenotypes also dictate the potential for unique coloration, such as deep purples, reds, or blues, which is often linked to the production of anthocyanins.
Why Phenotype Selection Matters to Cultivators
For commercial cultivators, the process of phenotype selection, known as “pheno-hunting,” is a lengthy but necessary step in strain development and refinement. This process involves starting dozens or even hundreds of seeds from a single genetic cross to observe the full range of phenotypes expressed under controlled conditions. The goal is to identify the single “keeper” plant that exhibits the most commercially desirable combination of traits, such as maximized yield, potent chemical profile, and robust growth structure.
Selection criteria are based on the traits detailed in the phenotype, including resistance to pests and mold, desirable bud structure, and the final cannabinoid-to-terpene ratios that meet market demand. Once a superior phenotype is identified, the mother plant is often referred to as an “elite clone,” and the rest of the plants from the seed batch are typically discarded.
Growers stabilize the selected phenotype by taking cuttings, or clones, from the mother plant, ensuring a consistent product. Cloning is a form of asexual or vegetative reproduction that creates genetically identical copies of the original plant, locking in the desired phenotypic expression for consistent, repeated harvests. This consistency is paramount for the commercial market, where consumers expect a predictable experience. By relying on clones of a single, proven phenotype, cultivators can guarantee uniformity in potency, flavor, and appearance across their entire production cycle.
Environmental Factors and Phenotypic Expression
While the genotype sets the limits of potential, the final expressed phenotype is significantly molded by the environment in which the plant is grown. This relationship highlights that the phenotype is a product of both genetics and external factors, often summarized by the equation Genotype + Environment = Phenotype. Even genetically identical clones grown in different settings will display noticeable variations in their final characteristics, especially regarding secondary metabolite production.
Environmental variables such as light intensity, temperature, humidity levels, and the precise nutrient composition of the soil or medium all influence the degree of gene expression. For example, some phenotypes possess the genetic potential for deep purple coloration, but this trait only fully manifests if the plant is exposed to cooler temperatures during the late flowering stage. Nutrient availability can also alter a phenotype’s growth rate and final yield size, influencing the overall morphology and chemical output of the plant.