Just like people, every cannabis plant has its own unique combination of DNA (or cannabis genetics), environmental influences, and chemical makeup that shape how it grows and how it feels.
Understanding cannabis genetics isn’t just for breeders or botanists — it’s essential for anyone who wants to understand how cannabis strains are made, how effects vary, and why one grow can produce different phenotypes even from the same genotype.
This is your crash course in cannabis genetics 101: understanding genotype, phenotype, and chemotype differences — what those terms mean, how they work together, and why they matter for growers, consumers, and the future of the cannabis industry.
what is cannabis genetics?
Cannabis genetics is the study of the plant’s DNA, aka the genetic code that determines its growth, appearance, aroma, potency, and overall chemical composition.
Every cannabis variety, from cannabis sativa to cannabis indica, contains unique genetic information. Those genes control everything from leaf shape to THC and CBD levels, and even how the plant responds to environmental factors like temperature and light.
For breeders and cultivators, genetics acts as a blueprint. Understanding them helps them selectively breed cannabis plants for desired traits like higher cannabinoid content, faster flowering times, or specific terpene profiles.
For cannabis users, genetics explain why one strain helps with chronic pain while another inspires creativity or encourages relaxation.
cannabis genotype and phenotype
genotypes
A cannabis genotype refers to the plant’s genetic instructions. Its complete DNA sequence determines what it can become.
Every seed carries a unique combination of traits inherited from its parent plants. Breeders can cross two plants to produce multiple seeds, each with a distinct genotype. That’s why even seeds from the same batch can grow into individual plants with subtle differences.
- growth patterns – how tall or bushy a plant gets
- yield – how much bud it produces
- resilience – how well it resists pests or temperature swings
- chemical composition – what cannabinoids and terpenes it’s capable of producing
The genotype is the foundation, but it’s not the full story. What we actually see or experience — the plant’s color, smell, or potency — depends on the environment it grows in. That’s where phenotype comes in.
phenotypes
A cannabis phenotype is how a plant’s genetic potential (its genotype) is expressed in the real world. Phenotype refers to the physical characteristics that result from both genetic makeup and environmental conditions.
In simpler terms, the genotype is the recipe, and the phenotype is the dish.
Two plants with the same genotype can grow to have different phenotypes if they’re raised in different environments—say, one under LED lights in a humid indoor grow, and another outdoors in dry mountain air.
Environmental factors like light exposure, temperature, humidity, nutrients, airflow, and soil type all influence how the plant’s genes express themselves.
That’s why even the same strain can produce slight differences in aroma, flavor, color, or potency, especially when grown in separate conditions.
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the relationship between genotype vs phenotype
The genotype gives the plant its genetic code, while the phenotype is the physical expression of that code.
- The genotype sets the boundaries for what’s possible.
- The phenotype shows what’s actually achieved in a specific environment.
That’s why cannabis breeders and cultivators care deeply about both. Breeding focuses on selecting plants with the right genetic variations, while cultivation focuses on creating the best environmental conditions to express those traits fully.
cannabis chemotypes
A cannabis chemotype refers to the plant’s chemical composition, or its unique combination of cannabinoids, terpenes, and other compounds. Chemotypes determine how a strain affects the body and mind.
There are three general categories of cannabis chemotypes:
- type I (high THC) – strong psychoactive effects, often used recreationally.
- type II (balanced THC: CBD) – mild euphoria with therapeutic benefits.
- type III (high CBD) – minimal intoxication, often used for medicinal properties like anxiety or pain relief.
Each chemotype can have different dominant cannabinoids, such as THC, CBD, or CBG, and a distinct terpene profile that shapes the scent and overall experience.
Cannabis breeders selectively breed cannabis plants to achieve specific chemotypes. For example, some cultivars are bred to emphasize anti-inflammatory cannabinoids for medical use, while others are designed to deliver energizing or relaxing effects.
cannabis seeds and breeding
When two parent plants are bred, they produce seeds containing new combinations of genetic traits. These seeds carry the genetic code of both parents, but no two are identical.
Breeders use several techniques to refine genetics:
- crossbreeding: mixing two different strains to create a hybrid with desired traits.
- backcrossing: breeding a hybrid with one of its parents to stabilize specific characteristics (like aroma or potency).
- pheno-hunting: selecting the best-performing phenotypes from multiple seeds.
Stable genetics are essential for growers who want predictable results and high-quality cannabis products. The goal is to achieve stable genetics, meaning every plant grown from the same seeds expresses consistent phenotypic traits like higher yield, cannabinoid ratio, or disease resistance.
environmental influences on cannabis plants
Even the most genetically perfect plant depends on the environment around it. The environmental factors that influence cannabis cultivation are the difference between a good grow and a great one.
These include:
- light exposure: affects photosynthesis and bud density.
- temperature: impacts metabolic rate and terpene production.
- humidity: regulates water loss and nutrient absorption.
- airflow: prevents mold and supports strong stems.
- soil nutrients: influence growth speed and flavor development.
Because cannabis is such a responsive plant, even slight variations in these factors can produce different phenotypes. Growers who fine-tune environmental controls can shape the plant’s overall quality, improving flavor, potency, and aroma.
pheno-hunting and cannabis cultivars
Pheno-hunting is the process of growing cannabis from multiple seeds of the same strain to find the best cannabis plants that express the most desirable traits.
Those traits might include:
- rich aroma and terpene concentration
- higher THC or CBD levels
- resistance to pests
- faster flowering
- specific physical characteristics like color or bud density
Once the best phenotypes are identified, breeders can clone them or use them for seed production to maintain those traits in future generations.
This process gives rise to cannabis cultivars. A cultivar (short for “cultivated variety”) is what we typically call a strain. Each cultivar has its own genetic makeup, chemical composition, and phenotypic expression, making every one unique in its effect and personality.
cannabis clones and preservation
A cannabis clone is an exact genetic copy of a parent plant. It’s produced by taking a cutting from a mature plant during its vegetative stage and allowing it to grow roots; this process is much like propagation.
Because clones share the same genetic instructions as their parent, they’re guaranteed to produce the same physical expression, chemical makeup, and phenotypic traits. Cloning is essential for:
- maintaining stable genetics
- preserving elite strains with desirable profiles
- ensuring consistent quality in commercial cannabis cultivation
Clones are a shortcut to reliability. They allow for identical plants with predictable results, eliminating the genetic variability found in seeds.
polyhybrids and crossbreeding
Modern cannabis is built on crossbreeding: the process of mixing two or more parent plants to create new, unique genetic variations.
A polyhybrid is a strain that results from multiple generations of crossbreeding. Most new strains you see today, like Gelato, Wedding Cake, or Runtz, are polyhybrids, created by blending several genetics over time.
Human intervention with genetics allows breeders to refine traits and create cannabis products that meet consumer demands. Crossbreeding also fuels innovation in the cannabis industry, leading to cultivars that are more disease-resistant, climate-adaptive, and chemically diverse.
the science behind every strain
At its core, cannabis is both art and science. Behind every puff or dab is a complex dance between genotype, phenotype, and chemotype—the invisible blueprint that defines how the cannabis plant grows, smells, tastes, and feels.
Understanding these differences helps us see cannabis not just as a product, but as a living system — one that reacts, adapts, and evolves based on its environmental factors and genetic code.
