The question of whether an autoflowering plant will produce autoflowering seeds is common, and the answer is rooted in genetics. The seeds produced depend entirely on the genetic makeup of both parent plants involved in the cross. The resulting seeds can be 100% autoflowering, entirely photoperiod-dependent, or a mix of both types. Understanding the specific genetic mechanisms that govern this trait is necessary to predict the outcome of any seed batch.
What Defines an Autoflowering Plant
Autoflowering plants are defined by a unique biological mechanism that controls their transition into the flowering stage. Unlike traditional photoperiod-dependent plants, which require a specific change in the light cycle to begin flowering, autoflowers do not. They are often described as “day-neutral” because they are not sensitive to the length of the day or night.
The decision to flower is based on the plant’s age, functioning on an internal biological clock. This programming causes them to transition from the vegetative stage to the flowering stage automatically, typically within two to four weeks after germination. This trait originates from Cannabis ruderalis, a subspecies that evolved in regions with short growing seasons. This characteristic allows the plants to complete their lifecycle rapidly, often going from seed to harvest in as little as 8 to 12 weeks.
The Genetic Inheritance of Autoflowering
The autoflowering trait is controlled by genetics and behaves in a specific, predictable manner. It is considered a simple, recessive trait. A recessive trait is only physically expressed when the plant inherits two copies of the specific gene, one from each parent.
Geneticists use letters to represent the trait, typically using a capital letter for the dominant trait (photoperiod dependency) and a lowercase letter for the recessive trait (autoflowering). A plant that exhibits the autoflowering trait must possess two copies of the recessive gene, a condition known as homozygous recessive.
In contrast, a plant that only has one copy of the recessive gene and one copy of the dominant gene is called heterozygous. A heterozygous plant will not flower automatically because the dominant photoperiod gene masks the recessive autoflowering gene. This plant is a carrier of the autoflowering trait, meaning it can still pass the recessive gene on to its offspring. For a seed to grow into an autoflowering plant, it must inherit the recessive autoflowering gene from both parents.
Seed Outcomes Based on Parentage
The outcome of the seeds produced depends entirely on the genetic makeup of the two parent plants that are crossed. When an autoflowering plant is crossed with another true-breeding autoflowering plant, the result is straightforward. Since both parents are homozygous recessive, they can only pass on the autoflowering gene, and 100% of the resulting seeds will grow into autoflowering plants.
A more complex scenario arises when an autoflowering plant is crossed with a photoperiod plant that is homozygous dominant, meaning it does not carry the autoflowering gene. In this first generation cross (F1 generation), 100% of the seeds will be heterozygous carriers. Because the photoperiod trait is dominant, all F1 plants will exhibit photoperiod behavior, requiring a change in the light cycle to flower.
The recessive trait only reappears in the next generation (F2), produced by crossing two F1 carrier plants together. According to Mendelian genetics, this cross yields a predictable ratio: 25% of the seeds will be homozygous recessive, meaning they will be true autoflowering plants. The remaining 75% will be photoperiod plants, with 50% being heterozygous carriers and 25% being homozygous dominant photoperiod plants. Breeders must grow out these F2 seeds and select the plants that flower automatically to continue their autoflowering line.