Pruning techniques in marijuana plants

In this article we will explore in depth the main pruning and training techniques that can be applied to cannabis plants to optimize their production. We will analyze LST (Low Stress Training), Supercropping, lollipopping, topping and FIM pruning. Each of these techniques offers specific advantages that adapt to different growing spaces and grower needs. It is essential to remember that any type of pruning or cutting must always be done with material previously sterilized with alcohol to prevent infections and diseases in the plants.

LST (Low Stress Training)

LST, or Low Stress Training, is a plant training technique that consists of gently bending and tying stems and branches to modify the natural growth pattern of cannabis, directing it towards a more horizontal structure optimized for light capture.

This technique has its roots in ancestral agricultural practices. It is believed that similar methods were used in ancient Egypt to grow fig trees horizontally more than 3,000 years ago. In 17th century Europe, the method known as "espalier" became popular, frequently applied to apple and pear trees not only to obtain better harvests but also to beautify the landscape.

How does LST work?

Cannabis naturally presents what is known as apical dominance, where the plant concentrates its energy on the main stem and central cola, leaving lateral branches less developed. LST breaks this apical dominance through physical manipulation of the plant, without the need to make cuts or pruning.

By bending the main stem and branches to the sides and tying them in a horizontal position, all parts of the plant are exposed to a more uniform amount of light. This redistributes growth hormones (auxins) more evenly throughout the plant, promoting the development of multiple main colas instead of a single dominant cola.

When to apply LST

The ideal time to start with LST is when plants have between 3 and 6 nodes. In this early growth phase, the stem is still flexible and moldable without risk of breakage. It is important to start when seedlings are young, since if you try to perform the technique with adult specimens it is very easy to end up breaking a branch due to the rigidity of the lignified stem.

Unlike other more aggressive techniques, LST can be applied throughout the vegetative period and even during flowering, which is a great advantage over pruning, which is not recommended once bud formation has begun.

Materials needed for LST pruning

• Soft gardening ties or rubber-coated wire: It is essential not to use normal ropes, fishing lines or materials that could damage or strangle the stem.
• Bamboo canes or stakes: To provide anchor points.
• Hand drill: To make holes in the edge of the pots where to tie the ropes.
• Adhesive tape: In case of accidental breakage.

How to proceed with LST pruning?

The first step is to bend the main stem so it grows horizontally instead of vertically. This is done gradually, bending the plant little by little each day until reaching the desired position. It is recommended to perform the technique after watering the plants, as this provides greater flexibility to the stem.

A soft ring should be tied around the stem, connected with a rope to the edge of the pot or to a stake. It is crucial that the fastenings leave slack and are not knots that strangle the stem. As the plant grows, it will be necessary to repeat the process and adjust the ties periodically, since the stem increases in thickness and the knots can end up tightening more than they should.

Advantages of LST

• Increased yield: By creating multiple main colas that receive direct light, the production of dense buds is significantly increased.
• Height control: Ideal for crops with limited vertical space, both indoors and in discreet outdoor settings.
• Low stress: Does not slow down plant growth like other more invasive techniques.
• Versatility: Can be applied at any stage of cultivation.
• Better light penetration: All parts of the plant receive light more evenly.
• Compatible with autoflowers: Unlike high stress techniques, LST is safe for autoflowering varieties.

Supercropping - controlled high stress technique

Supercropping, also known as HST (High Stress Training), is an advanced cultivation technique that consists of strategically bending and pinching the plant's branches to influence its growth pattern and stimulate greater production of cannabinoids and terpenes.

Why apply supercropping?

When Supercropping is applied, the internal fibers of the stem (xylem, phloem and cambium) are broken without damaging the outer bark. This process momentarily interrupts the flow of nutrients, water and hormones to the apical tip, redirecting them towards the lower areas of the plant.

The plant responds to this "controlled damage" by repairing the affected area through the formation of a callus of thicker and more resistant tissue. This thickening subsequently allows a greater flow of liquids, nutrients and hormones through that branch, which translates into more vigorous development and greater flower production.

Additionally, controlled stress triggers a defensive response in the plant that increases the production of resin, cannabinoids and terpenes, as these compounds are part of cannabis's natural defense mechanism.

How to perform supercropping

The technique is surprisingly simple but requires practice and delicacy:

1. Branch selection: Identify the branches you want to manipulate, preferably those that are growing taller than the rest to level the canopy. Choose mature branches but not too woody or too young and fragile.
2. Application point: Select a point on the branch, generally about 7 cm from the tip, in the area between nodes. Avoid applying the technique on the 2-3 nodes closest to the tip.
3. Pinch and bend: Hold the branch firmly between your thumb and index finger. Apply gentle pressure while moving and slightly twisting the stem. You will feel or hear a slight snap when the internal fibers break (in 5-10 seconds the branch will become more flaccid).
4. Bending: Once the area is softened, carefully bend the branch at a 90-degree angle or more in the desired direction.
5. Fastening: If necessary, use soft ties or canes to keep the branch in the bent position until it recovers.

When to apply supercropping?

Supercropping should be applied mainly during the late vegetative phase, ideally between 3-7 days before starting flowering. This allows plants to recover from stress before focusing their energy on bud production.

For experienced growers, it is possible to apply a second session during the first two weeks of flowering, taking advantage of the "stretch" period where plants have explosive growth. However, it should never be done in the final flowering phase, when plants are concentrated on flower maturation.

Advantages of supercropping

• Increased production: Between 10-20% increase in harvest according to growers' experiences.
• Greater potency: Controlled stress stimulates the production of cannabinoids and terpenes.
• More robust plants: The callus formed strengthens the plant's structure.
• Height control: Allows leveling the canopy in mixed crops.
• No tools required: Only hands are needed (and optionally adhesive tape).
• Better light distribution: Bent branches allow light to reach lower areas.

Precautions with supercropping pruning

Supercropping is a high stress technique and is not suitable for plants that are already experiencing other types of stress (pests, nutritional deficiencies, watering problems). It is also not recommended for autoflowering plants, as their short vegetative cycle does not allow them to adequately recover from the stress caused.

Lollipopping (lower pruning)

Lower pruning, popularly known as Lollipopping, is one of the most used techniques by indoor growers, consisting of removing branches, leaves and shoots from the lower third of the plant to concentrate all energy on the development of higher quality upper buds.

Where does the name lollipopping come from?

The name "Lollipopping" comes from the English term "lollipop", due to the characteristic appearance that the plant acquires after pruning: a clean and bare stem in its lower part with a dense concentration of foliage and flowers in the upper part, similar to a lollipop.

Fundamentals of lollipopping

In indoor cultivation, artificial light is positioned statically at the top of the growing space. Due to the inverse square law of light intensity, light loses intensity rapidly as distance from the source increases. Lower branches, being shaded by the upper canopy, receive very little direct light and produce small, not very dense and lower quality flowers (known as "popcorn buds").

By eliminating these unproductive parts, the plant can redirect all its energy, nutrients and hormones towards the upper areas where there is abundant light, resulting in larger, denser and more resinous buds.

Benefits of lower pruning

• Resource optimization: The plant concentrates its energy on producing higher quality flowers instead of wasting it on small and unproductive buds.
• Improved air circulation: By eliminating dense lower foliage, better airflow is allowed, reducing humidity and preventing the appearance of fungi such as botrytis and mildew.
• Facilitates maintenance: With the base of the crop cleared, it is easier to inspect plants, detect pests and perform watering and fertilization tasks.
• Prevention of hermaphroditism: In stress situations, plants can develop pollen sacs, which tend to appear on lower branches. Lollipopping eliminates these problematic areas.
• Uniform harvest: All main buds mature more homogeneously.
• Lower risk of mold: By distributing production into medium-sized buds instead of excessively bulky flowers, the risk of rot is reduced.

When to perform lower pruning?

The optimal time to apply lollipopping is a matter of debate among growers. The two main schools are:

• During late vegetative phase: Performing pruning 1-2 weeks before changing the photoperiod to flowering allows the plant to recover from stress without affecting bud development.
• At the beginning of flowering: Some growers prefer to wait to see the first preflowers to decide which shoots to keep, performing pruning during the first 15-20 days of flowering.

As a general rule, lower pruning should be completed before 20 days of flowering. After this period, any pruning can excessively stress the plant and reduce final production.

How to perform lower pruning

1. Inspection with lights on: Turn on the grow lights and step back to observe the plants from a distance. Identify the shaded areas that do not receive direct light.
2. Determining pruning height: Generally the lower third of the plant is removed, although in indoor crops with poor light penetration it can be up to 50% of the lower part.
3. Tool preparation: Use sharp pruning scissors sterilized with isopropyl alcohol.
4. Branch removal: Cut lower branches at their base, as close as possible to the main stem, with a clean cut. Remove between 5-8 branches depending on plant size.
5. Cleaning small shoots: Remove all small shoots and yellowing or dry leaves from the lower area.
6. Final result: The plant should have an "umbrella" appearance with a clean and bare stem at the base and all vegetation concentrated in the upper part.

Considerations for outdoor

In outdoor cultivation, lollipopping is usually not as necessary because the sun moves in different directions during the day, illuminating all parts of the plant. Additionally, fan leaves function as energy generators thanks to photosynthesis. It is only recommended outdoors when it is known that lower buds will end up full of dirt or exposed to high environmental humidity.

Combination with other pruning techniques

Lollipopping complements perfectly with other techniques such as SCROG (Screen of Green), LST or Main-Lining, significantly enhancing results.

Topping (apical pruning)

Apical pruning, internationally known as "topping", is one of the most popular and effective training techniques in cannabis cultivation. It consists of cutting the tip of the plant's main stem during the vegetative phase to break apical dominance and stimulate the growth of multiple main colas.

Principle of apical dominance

Cannabis plants, like many other plant species, naturally present apical dominance. This means that the apex or growth tip of the main stem produces growth hormones called auxins that inhibit the development of lower lateral branches, concentrating energy on vertical growth.

By physically eliminating this dominant apex through a cut, the production of auxins at that point is interrupted, causing these hormones to be redistributed towards lateral shoots. As a result, the two shoots that were just below the cut are activated and begin to grow vigorously, becoming two new main stems.

When to perform apical pruning?

The right timing is crucial for the success of this technique. Apical pruning should be performed when the plant has developed between 3 and 5 nodes or pairs of true leaves, generally between weeks 3 and 4 of vegetative growth.

At this stage, the plant already has enough strength, stature and root development to withstand the stress of the cut and recover adequately. If done too early, the plant can go into shock and suffer severe developmental delay. If done too late, with very lignified stems, recovery will be slower.

How to perform apical pruning?

1. Preparation: Sterilize sharp pruning scissors with isopropyl alcohol. It is essential to use well-sharpened tools to make a clean cut, as dull scissors can crush the stem instead of cutting it.
2. Identifying the cut point: Locate the apical node (the newest shoot at the tip of the main stem). Generally it is cut just above the third or fourth node.
3. Making the cut: Make a clean and horizontal cut just above the selected node, leaving approximately 5mm of stem between the cut and the lateral branches. This margin of error avoids accidentally damaging lateral shoots.
4. Post-pruning care: After cutting, the plant will need between 4-7 days to recover. During this period it is crucial to maintain optimal conditions: adequate watering, balanced nutrition and stable environment.

Results of apical pruning

After cutting, the two lateral shoots that were just below begin to grow in a "Y" shape, becoming two new main stems. This doubles the number of main colas that will produce dense and voluminous buds.

It is possible to perform multiple apical prunings on the same plant. Each time one of the new main branches is pruned, they will divide again into two, creating 4, 8, 16 main colas, etc. However, each additional pruning requires more recovery time in vegetative phase.

Advantages of apical pruning

• Significant production increase: By creating multiple main colas instead of a single one, total yield is notably increased.
• Height control: Stops vertical growth, ideal for spaces limited in height.
• Uniform canopy: Allows more homogeneous light distribution over multiple flowering points.
• Greater resin production: Controlled stress stimulates the plant's defenses, increasing trichome production.
• More compact structure: Results in wider and bushier plants instead of tall and thin ones.

Disadvantages and precautions

• Prolonged vegetative phase: The plant needs 4-6 weeks of vegetative phase to fully recover from pruning and reach its maximum potential.
• Risk of infections: The cut leaves an open wound that can be a gateway for fungi and pathogens if conditions are not optimal.
• Greater susceptibility to stress: Pruned plants that subsequently suffer other problems (pests, deficiencies, overwatering) will have more difficulties recovering.
• Risk of hermaphroditism: Excessive stress can cause plants to develop male sex organs and self-pollinate.
• Not recommended for autoflowers: Autoflowering varieties have a fixed and short life cycle that does not allow enough time to recover from the stress of apical pruning.

Combination with other techniques

Apical pruning can be successfully combined with techniques such as LST, SCROG, Main-Lining or Lollipopping to further maximize results. Many professional growers use multiple techniques together to fully optimize growing space and production.

FIM pruning (Fuck I Missed)

FIM pruning is a high stress technique derived from apical pruning, discovered by accident in the 90s. Its peculiar name comes from the English expression "Fuck, I Missed", pronounced by an American grower who was trying to perform apical pruning and missed the cut, only partially removing the plant's apex.

The story behind FIM

Legend has it that this somewhat careless grower was apically pruning his plants directly with his fingers instead of using scissors. When making cuts without much precision, in several cases he had not removed the complete shoot but only part of it. His surprise came days later, when he observed that instead of obtaining two new shoots (as occurs with traditional apical pruning), he had obtained 4 or more new main branches on the "badly pruned" plants. Thus one of the most effective cola multiplication techniques was accidentally born.

Difference from apical pruning

The fundamental difference between both techniques lies in the amount of tissue that is removed:

• Apical pruning: 100% of the apex is removed, completely cutting the upper shoot. Result: 2 new main colas.
• FIM pruning: Approximately 75-80% of the apex is removed, leaving a small portion of the shoot. Result: Between 4 and 8 new main colas.

Fundamentals of FIM pruning

Cannabis plants present a high concentration of nodes per centimeter in the apical bud. Each node has the potential to generate new branches. By cutting only partially the apex at the exact place, simultaneous branching of multiple nodes is forced, with between 4 and 10 new shoots appearing instead of just two.

The challenge of the FIM technique lies precisely in finding that "sweet spot" to maximize the number of branches. Cutting at the ideal spot requires practice and experience, so results can be somewhat unpredictable at first.

How to perform FIM pruning

1. Proper timing: Same as with apical pruning, it should be performed when the plant has between 3 and 5 developed nodes, during the vegetative phase.
2. Preparation: Sterilize your pruning scissors or, if you feel experienced, you can use your fingers (like the original inventor of the technique).
3. Identifying the point: Locate the new shoot at the tip of the main stem. The cut should be made just where the two leaves that make up the new shoot are born.
4. Executing the cut: With one hand, hold firmly but carefully the tip of the upper stem. With the other, cut approximately 75-80% of the upper shoot at an angle, leaving visible a small remnant (20-25%) of the apex.
5. Recovery: In 3-7 days you will begin to see new shoots emerging from the cut.

Tip: Leave at least one lower node uncut before performing FIM pruning. This ensures that, in the worst case, if something goes wrong, you will still have a pair of branches that can continue growing.

Advantages of FIM pruning

• Cola multiplication: Can generate between 4 and 8 new main branches from a single cut, surpassing apical pruning which only generates 2.
• Optimal space utilization: Ideal for crops with few plants where you want to maximize production per specimen.
• Greater bud surface: By having more main colas, available light is better utilized.
• Ideal for SCROG: The multiplication of tips is perfect for filling a SCROG screen with fewer plants.
• Clone production: Excellent for mother plants, as it multiplies the number of apical tips available for making quality clones.
• Moderate height control: Although it does not stop vertical growth as much as apical pruning, it does slow it down significantly.

Disadvantages and considerations

• Unpredictable results: The exact number of new branches can vary depending on the precision of the cut and the plant's genetics.
• Requires practice: Finding the exact cutting point to maximize branches is an art that is mastered with experience.
• Less effective for height control: Does not stop vertical growth as effectively as apical pruning, so it should be combined with LST or SCROG.
• Thinner branches: By multiplying colas so much, they can be thinner and more flexible, requiring supports during flowering to bear the weight of buds.
• Not recommended for autoflowers: Like apical pruning, the stress caused is not suitable for the short life cycle of autos.
• Impractical in large crops: In commercial facilities with many plants, the time required to apply FIM to each specimen makes other techniques like SOG or SCROG more efficient.

Multiple applications

FIM pruning can be applied "infinitely", being able to be performed first on each bud and then on each of the new buds that were generated with the first pruning. However, each additional application requires recovery time, significantly prolonging the vegetative phase.

Combination with other pruning techniques

FIM pruning is greatly enhanced when combined with:

• SCROG: Multiple colas are perfectly distributed on a screen to create a uniform canopy.
• LST: Allows directing each of the new branches to optimize light exposure.
• Lollipopping: Removing lower branches concentrates all energy on the multiple upper colas generated by FIM.

Final recommendations

Each of these pruning and training techniques offers unique advantages that adapt to different growing situations:

• LST: Ideal for beginners, autoflowers and when seeking low stress with good results.
• Supercropping: For experienced growers seeking to maximize potency and yield through controlled stress.
• Lower pruning: Essential in indoor crops to eliminate unproductive areas and concentrate energy on quality upper buds.
• Apical pruning: Perfect for doubling the number of colas and controlling height, requires photoperiodic plants with sufficient time in vegetative.
• FIM pruning: Excellent for multiplying colas in crops with few plants, ideal combined with SCROG.

Choosing the right technique will depend on multiple factors: available space, cultivated genetics, grower's experience level, time available in vegetative phase and specific production goals. Many experienced growers combine several techniques to maximize their results to the fullest.

Always remember: Any intervention on plants must be done with sterilized tools, on healthy plants and under optimal environmental conditions. Patience, observation and continuous learning are the keys to success in cannabis cultivation.

Which of these techniques seems most suitable for your crop? Experimentation and practice are fundamental to mastering these techniques and finding the method that best suits your specific needs.