Plant Growth Regulators (PGR’s) in Cannabis: Understanding the Differences Between Natural and Synthetic Regulators

Plant Growth Regulators (PGR's) in Cannabis: Understanding the Differences Between Natural and Synthetic Regulators

Plant Growth Regulators (PGR’s) in Cannabis: Understanding the Differences Between Natural and Synthetic Regulators


As the cannabis industry continues to grow, so does the knowledge and understanding of the factors that contribute to optimal plant growth and health. One crucial aspect of plant growth and development is the role of plant growth regulators (PGRs). PGRs are chemical substances that play a significant role in various processes such as cell division, elongation, and differentiation. This article will discuss the term plant growth regulators in cannabis plants, the differences between naturally occurring and synthetic plant growth regulators, and provide a list of both natural and synthetic PGRs.

What are Plant Growth Regulators (PGRs)?

Plant growth regulators, also known as phytohormones or plant hormones, are organic compounds that regulate plant growth and development. PGRs are produced naturally within the plant, and they help control various physiological processes such as germination, flowering, fruit development, and senescence. They act in small concentrations and can have either stimulating or inhibiting effects on plant growth, depending on the type of hormone and its concentration.

Natural vs. Synthetic Plant Growth Regulators

Natural PGRs are organic compounds synthesized and secreted within the plant. They play a vital role in maintaining the plant’s overall health and growth. Synthetic PGRs, on the other hand, are man-made chemicals that mimic the action of natural PGRs. Synthetic PGRs are often used in agriculture and horticulture to manipulate plant growth, improve yields, or control pests and diseases.

The use of synthetic PGRs in cannabis cultivation is a controversial topic due to potential health risks and negative effects on the plant’s quality. While synthetic PGRs can provide immediate and noticeable results, they may cause adverse effects on the plant and the end product, including reduced terpene production and potential contamination with harmful residues.

Natural Plant Growth Regulators


Auxins are primarily responsible for cell elongation and differentiation. They play a crucial role in various processes, such as apical dominance, root initiation, and fruit development. Indole-3-acetic acid (IAA) is the most common naturally occurring auxin in plants.

Gibberellins (GAs):

Gibberellins promote stem elongation, seed germination, and flowering. They are also involved in breaking seed and bud dormancy. There are over 100 different gibberellins, with Gibberellic acid (GA3) being the most widely recognized.


Cytokinins are involved in cell division, shoot, and root development, and delaying senescence in leaves. Some naturally occurring cytokinins include zeatin, kinetin, and isopentenyladenine.

Abscisic acid (ABA):

ABA plays a critical role in seed dormancy, germination inhibition, and response to environmental stresses, such as drought and cold.


Ethylene is a gaseous hormone that influences fruit ripening, leaf abscission, and senescence.

Synthetic Plant Growth Regulators

Synthetic auxins:

Synthetic auxins, such as 2,4-Dichlorophenoxyacetic acid (2,4-D) and Naphthaleneacetic acid (NAA), are often used for weed control and rooting of cuttings.

Synthetic gibberellins:

Some synthetic gibberellins, like ProGibb and Gibberellic acid (GA3), are used to promote flowering, fruit set, and seed germination.

Synthetic cytokinins:

Benzylaminopurine (BAP) and Thidiazuron (TDZ) are synthetic

cytokinins used to stimulate cell division, promote shoot development, and delay senescence.

Synthetic abscisic acid:

Synthetic ABA, such as S-ABA, is used to improve drought tolerance, induce seed dormancy, and promote fruit ripening.

Synthetic ethylene:

Ethephon is a synthetic ethylene compound used to induce fruit ripening, promote leaf abscission, and control plant growth.


Plant growth regulators play a crucial role in the growth and development of cannabis plants. Both natural and synthetic PGRs have their uses and effects on plant growth, but growers should exercise caution when using synthetic PGRs due to potential health risks and adverse effects on the quality of the final product. Understanding the role of PGRs in cannabis cultivation can help growers make informed decisions about the use of these compounds to optimize plant growth and ensure the safety and quality of their cannabis products.

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