Pruning to increase yield: how to prune cannabis, and what the research found

Pruning to increase yield works, within limits. In a 2022 indoor study, topped plants produced more dried flower than unpruned ones, but their total CBD yield was not significantly different. A 2021 greenhouse study found that clearing leaves and lower branches mostly evened out cannabinoid levels through the plant, while one repeated pruning schedule raised flower yield. For a home grower the lesson is to prune with a purpose: take off what gets no light, keep the leaves that feed the buds, and time the cuts around the stretch.

This is the pruning guide in our growing series. For the choice between bending and cutting the main stem, see LST versus topping; for the vocabulary, the grower’s glossary; and for the whole grow, our home-grow guide.

Last reviewed: November 2026.

Pruning to increase yield: what two studies found

Massuela and colleagues (2022) grew one CBD-dominant medical cannabis genotype indoors and compared three treatments: topping at the tenth node, a lollipop treatment that removed the lowest side branches, and an unpruned control. Pruning happened 27 days after planting. Topped plants produced significantly more dried flower and leaf than the other two, and pushed more of their flower toward the top of the plant. Total CBD yield showed a trend of topped above control above lollipop, but neither pruned group differed significantly from the control.

Danziger and Bernstein (2021) tested eight shaping treatments on Topaz, a high-CBD cultivar grown to about 2.5 meters in a greenhouse. Defoliation and removing bottom branches and leaves let more light into the lower canopy and raised cannabinoid concentrations there, making the plant more uniform. Flower yield moved for only two treatments: a double prune, with a second cut at the switch to flowering, gave more, and stripping the primary branches gave less.

Both studies used CBD-type plants in research settings, and a home tent will behave differently. Their findings still line up with what the university grow guides advise.

How to prune marijuana plants during vegetative growth

Step 1: remove dead or damaged leaves as soon as you see them. The University of Saskatchewan grow guide says that applies whatever your pruning style.

Step 2: do any shaping cuts, such as topping or pinching growth tips, during vegetative growth. USask’s vegetative guide describes training as optional and done to control size and shape. Our LST versus topping guide covers how to choose.

Step 3: clean the blade between plants. OSU Extension says hop latent viroid moves on tools through plant sap, and that bleach solutions inactivate it where ethanol and hydrogen peroxide do not.

If fan leaves turn yellow during veg, look at feeding and watering before you reach for the snips. USask notes that nitrogen is usually the limiting nutrient in vegetative growth and that overwatering damages roots. Cutting yellow leaves treats the sign, and the cause stays.

Trimming during the flower stage: lollipopping and fan leaves

Hold off early. USask advises against pruning branches in early flower because it can cause stretching beyond what the plant would do anyway. Its recommended window is the transition from early to late flower, about 3.5 to 4 weeks after you switch to 12 hours of light for most varieties.

At that point, take the lower leaves that get no light, especially ones covering bud sites, and the small lower branches. USask says those branches rarely produce good flower under the canopy, and clearing them improves airflow and cuts harvest work. That is lollipopping in all but name.

Can you remove all the fan leaves during flowering? You can, but the USask author does the opposite and leaves as many as possible, because leaves photosynthesize and store nutrients the plant can draw on later. As long as the canopy is full and using the light, the plant is in good shape.

Outdoor plants need even less. USask says flower-stage leaf pruning is generally unnecessary outside, because the sun reaches every part of the plant. Dead or damaged leaves still come off.

The last cut: harvest trimming

The final round of pruning happens at harvest. The USask harvesting guide describes wet trimming, where you cut branches, strip fan leaves and manicure sugar leaves right away, and dry trimming, where you hang the plant whole and trim after it dries. Wet trimming speeds drying; dry trimming is handy when you need to harvest but cannot spend hours trimming that day.

Either way, save the trim if you like: USask notes that some growers collect the resinous sugar leaves for hash or edibles. Keep the plant count in mind as you plan the next round, too: Health and Safety Code section 11362.2(a)(3) allows not more than six living plants per private residence in California, however many adults live there. This is general information, not legal advice.

Frequently asked questions

Sources

• California Health and Safety Code section 11362.2
• Massuela et al. 2022, Plants: Harvest time and pruning technique in medicinal cannabis
• Danziger and Bernstein 2021, Plants: Shape matters
• USask: Flowering
• USask: Vegetative growth
• USask: Harvesting and trimming
• OSU Extension: Hop latent viroid in hemp
• DCC: What's legal

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