Pruning selectively removes unnecessary foliage, redirecting the plant’s energy into producing larger, denser, higher-quality buds. It also improves plant morphology, resulting in a better microclimate by increasing light exposure and air circulation around the plant.
Cannabis exhibits monopodial growth, meaning it develops a single main stem that grows vertically, and because it is apically dominant,[1] the main stem inhibits the growth of lateral shoots. Pruning the main stem relieves the plant of apical dominance, triggering hormonal changes—specifically, changes in auxin and cytokinin levels—that stimulate side shoot development. Studies suggest this can increase inflorescence yield and CBD production.[2] However, the plant’s response depends on genetics and growth patterns, so understanding when and how to prune is critical for capturing benefits.
Pruning methods
There are four common pruning methods for cannabis cultivation:[3]
- Topping: Removes the top of the main shoot to break apical dominance, encouraging lateral branch growth and creating a bushier plant with multiple colas.
- Fimming: Pinches or snips off the new growth at the tip of the main shoot, leaving about 20–25% intact. This encourages multiple new shoots to form from the remaining tissue.
- Lollipopping: Clears branches and foliage from the lower third of the plant, redirecting energy to the top buds.
- Defoliation: Removes large fan leaves to improve light penetration, airflow and nutrient distribution to lower parts of the plant.
Figure 1. Overview of pruning techniques. Abbreviations: T = Topping; L = Lollipopping; C = Control. Image source: Crispim Massuela, Danilo, Jens Hartung, Sebastian Munz, Federico Erpenbach and Simone Graeff-Honninger. 2022. “Impact of Harvest Time and Pruning Technique on Total CBD Concentration and Yield of Medicinal Cannabis.” Plants 11(1): 140. https://doi.org/10.3390/plants/11010140.
Pruning methods
There are four common pruning methods for cannabis cultivation:[3]
- Topping: Removes the top of the main shoot to break apical dominance, encouraging lateral branch growth and creating a bushier plant with multiple colas.
- Fimming: Pinches or snips off the new growth at the tip of the main shoot, leaving about 20–25% intact. This encourages multiple new shoots to form from the remaining tissue.
- Lollipopping: Clears branches and foliage from the lower third of the plant, redirecting energy to the top buds.
- Defoliation: Removes large fan leaves to improve light penetration, airflow and nutrient distribution to lower parts of the plant.
Figure 1. Overview of pruning techniques. Abbreviations: T = Topping; L = Lollipopping; C = Control. Image source: Crispim Massuela, Danilo, Jens Hartung, Sebastian Munz, Federico Erpenbach and Simone Graeff-Honninger. 2022. “Impact of Harvest Time and Pruning Technique on Total CBD Concentration and Yield of Medicinal Cannabis.” Plants 11(1): 140. https://doi.org/10.3390/plants/11010140.
Benefits of pruning
Pruning offers multiple benefits to cannabis growers, primarily by allowing them to manipulate plant reproduction.
Cannabis has a constant phytomer structure, meaning its shoot growth follows a repetitive, predictable pattern. During flowering, the plant develops primary inflorescences along the main stem, secondary inflorescences along primary branches and so forth. Small- to medium-sized cannabis plants typically produce flowers up to the third or fourth order, while axillary buds along stems and branches also produce inflorescences.[4]
Because the plant’s architecture and amount of branching influence reproduction, selectively removing foliage helps redirect energy toward growth points, promoting larger, denser, higher-quality buds.[5]
Pruning, particularly the lower branches, also increases air circulation, reducing the risk of pests and disease, as well as light penetration, linked to higher yields and greater chemical uniformity.[6]
Research insights on pruning
Several studies have confirmed these benefits. One study found that pruning twice during the vegetative stage led to the greatest increase in yields among different pruning treatments, along with higher phytocannabinoid concentrations. CBDA and THCA increased by 59% and 50%, respectively, which researchers attributed to greater light intensity at different heights.[7]
The same study found that lollipopping at flipping, combined with defoliation three weeks before harvest, increased CBDA, THCA, CBDVA and THCVA concentrations. However, lollipopping alone did not affect yield or phytocannabinoids.[8] The researchers concluded that modifying the cannabis shoot architecture can improve cannabinoid standardization in large plants.[9]
Another study by the same researchers found that removing the first branch significantly reduced phytocannabinoids and yields in two high-THC cannabis cultivars, while lollipopping slightly increased CBDVA in one cultivar and CBCA in another.[10]
A third study determined that topping increased inflorescence dry matter and total CBD content in two industrial hemp cultivars.[11]
Figure 2. Main pruning techniques applied in cannabis cultivation: cover pruning (topping), defoliation and branch removal, with an approach to the benefits and possible effects on productivity. Image source: Trancoso, Ingrid, Guilherme A. R. de Souza, Paulo Ricardo dos Santos, et. al. 2022. “Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production.” Agronomy 12 (7): 1492. https://doi.org/10.3390/agronomy12071492.
Figure 2. Main pruning techniques applied in cannabis cultivation: cover pruning (topping), defoliation and branch removal, with an approach to the benefits and possible effects on productivity. Image source: Trancoso, Ingrid, Guilherme A. R. de Souza, Paulo Ricardo dos Santos, et. al. 2022. “Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production.” Agronomy 12 (7): 1492. https://doi.org/10.3390/agronomy12071492.
How to prune cannabis
Preparing to prune
The equipment required for pruning is simple. Growers need:
Trimming scissors: Thin, sharp, comfortable-to-hold scissors for cutting smaller branches and leaves. These allow for detailed work and help maintain a neat structure.
Pruning shears: Lightweight shears with ergonomic handles for pruning thicker branches.
Trimming scissors: Thin, sharp, comfortable-to-hold scissors for cutting smaller branches and leaves. These allow for detailed work and help maintain a neat structure.
Pruning shears: Lightweight shears with ergonomic handles for pruning thicker branches.
Disinfectant: Disinfecting agents like isopropyl alcohol prevent the spread of disease.
The vegetative phase is the best time to prune cannabis because plants are substantially growing and can recover quickly from pruning stress. Topping and fimming are most effective during early- to mid-veg to encourage lateral branching and a bushier plant structure.
Pruning after the vegetative phase should be done cautiously. As plants flip from veg to flowering, defoliation can enhance light distribution, but excessive leaf removal should be avoided to maintain photosynthetic capacity. In early flowering, pruning can help shape the canopy, improve light penetration and remove unnecessary lower branches (lollipopping), but heavy pruning late in the flower phase can stress the plant and divert energy from bud production.
Pruning step-by-step
Start by identifying which parts of the plant are thriving and which are unlikely to contribute to healthy growth. Removing unnecessary leaves and offshoots helps redirect energy to stronger top leaves and stems. Thereafter:
- Trim the main stem to encourage a bushier, outward-spreading structure rather than a tall, vertical one.
- Leave the top three nodes intact and remove larger branches that obstruct airflow or grow inward, as these can hinder the development of surrounding branches.
- Cut thick, misaligned branches and leaves first, making clean, 45-degree cuts close to the stem to reduce infection risk and promote faster healing.
- Eliminate any small, brown or diseased tissue to prevent the spread of infection.
- Inspect the plant after pruning to ensure all branches receive sufficient light and are not overshadowing others.
Pruning can shock the plant, so maintaining optimal temperature, humidity and lighting will support a smooth recovery. Avoid excessive pruning, as it can stress the plant and impede bud development.
Emerald Harvest Team
Blog Header Image by jcomp on Freepik
Trimming Scissors Image by brgfx on Freepik
Garden Shears Image by pch.vector on Freepik
Isopropyl Alcohol Image by studiogstock on Freepik
[1] Danziger, Nadav, and Nirit Bernstein. 2021. “Plant Architecture Manipulation Increases Cannabinoid Standardization in ‘Drug-Type’ Medical Cannabis.” Industrial Crops and Products 167 (1): 113528. https://doi.org/10.1016/j.indcrop.2021.113528.
[2] Trancoso, Ingrid, Guilherme A. R. de Souza, Paulo Ricardo dos Santos, et. al. 2022. “Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production.” Agronomy 12 (7): 1492. https://doi.org/10.3390/agronomy12071492.
[3] Ibid.
[4] Danziger, Nadav, and Nirit Bernstein. 2021. “Plant Architecture Manipulation Increases Cannabinoid Standardization in ‘Drug-Type’ Medical Cannabis.” Industrial Crops and Products 167 (1): 113528. https://doi.org/10.1016/j.indcrop.2021.113528
[5] Ibid.
[6] Danziger, Nadav, and Nirit Bernstein. 2021. “Shape Matters: Plant Architecture Affects Chemical Uniformity in Large-Size Medical Cannabis Plants.” Plants 10 (9): 1834. https://doi.org/10.3390/plants10091834.
[7] Trancoso, Ingrid, Guilherme A. R. de Souza, Paulo Ricardo dos Santos, et. al. 2022. “Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production.” Agronomy 12 (7): 1492. https://doi.org/10.3390/agronomy12071492.
[8] Ibid.
[9] Danziger, Nadav, and Nirit Bernstein. 2021. “Shape Matters: Plant Architecture Affects Chemical Uniformity in Large-Size Medical Cannabis Plants.” Plants 10 (9): 1834. https://doi.org/10.3390/plants10091834.
[10] Danziger, Nadav, and Nirit Bernstein. 2021. “Plant Architecture Manipulation Increases Cannabinoid Standardization in ‘Drug-Type’ Medical Cannabis.” Industrial Crops and Products 167 (1): 113528. https://doi.org/10.1016/j.indcrop.2021.113528.
[11] Folina, Antigolena, Ioanna Kakabouki, Evangelia Tourkochoriti, Ioannis Roussis, Harry Pateroulakis, and Dimitrios Bilalis. 2020. “Evaluation of the Effect of Topping on Cannabidiol (CBD) Content in Two Industrial Hemp (Cannabis sativa L.) Cultivars.” Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture 77 (1). https://doi.org/10.15835/buasvmcn-hort:2019.0021.