A Complete Guide to Topping, Training and Pruning Marijuana Plants

by Kodiak

How To Improve Your Marijuana Harvest

Table of Contents

• Introduction to Plant Training
• Topping
• Super Cropping
• LST Training
• Scrogging
• Sea of Green (SoG)

I got some requests for pointers on how to train your plants for a maximized crop, so I put this guide together. I will cover the basic idea behind the various techniques and how to apply them, sometimes in combination, for the best results. All of the techniques mentioned in this guide can be used both indoors and outdoors with equal results.

Introduction

At first glance plants seem simple but when we take a closer look at how they work we soon realize that they are in fact very complex. They rely on many different mechanisms of development and survival and are quite versatile when it comes to adaptation. Plants orientate themselves according to sunlight by a mechanism that is called phototropism. This means that the plant will always try to find the best way to capture the light by changing its shape and redirecting its leaves. Branches elongate, shoots twist and curl around obstacles in order to reach the light. The roots in turn orientate themselves according to gravity, which is called gravitropism. This means that if you tilt a potted plant on its side, it will grow into an s-shaped curve, shoots towards the sky and roots towards the earth. We are however only interested in phototropism as we can utilize this natural response in order to shape the plant as we see fit.

It sometimes helps to think of the plant as a factory, where the leaves are the solar panels that provide the energy needed for production. That in turn is directly dependant on the availability of raw materials (including CO2 and water), something that you have to provide for the plant. Some of the raw materials are absorbed through the roots, so they are just as important as the leaves. The production can be divided into growth (expansion) and upkeep or maintenance. Maintenance has higher priority, although the plant will also relocate energy from less productive areas to areas that are more efficient. You can assist the plant by pushing the production towards the top of the plant, where there is more light but more on this later. There are many other things that you need to factor in but assume that the plant is always trying to make the most out of what is available to it. Plants may appear to be static but they are in fact in a state of constant flux, where the energy equilibrium is always shifting and readjusting.

Cannabis plants grow in the triangular shape of a Christmas tree in the wild. This shape is the most efficient when a plant is part of a densely packed community. Seeds usually fall close to the mother plant and tight clusters of plants are formed. Outdoors the sun rises and sets and moves across the sky during the day, so every part of the plant receives some light at one point or the other. This is not the case indoors, where the light source is stationary. The light always comes from the same angle, usually from above. This means that the natural shape of the plant is perhaps no longer the most energy efficient and most of the time the light does not reach the lower parts of the plant. Our artificial lights simply do not carry the same strength as the sun and parts of the plant are left in the shade or at least receive less light that the top shoots. Height is also an issue indoors as we have limited space for the plants to grow in and cannabis plants can grow very tall.

Topping

Topping the plant means that you remove the main shoot located on the central stem. By doing so you will encourage the plant to grow into a bush with a lot of shoots instead of one big main shoot that you get on the untopped Christmas tree. You will effectively invert the triangular shape of the plant from a pyramid to a cocktail glass.

Topping the plant enables you to make the most out the the relatively limited light source that you have at your disposal in the indoor environment.

The reason why the plant behaves this way when it is topped is because the centre of growth control is located in the apical meristem or main shoot. The main shoot sends suppressive hormones down to the lower or axillary shoots which stops them from growing rapidly. This is called apical dominance. This mechanism does not stop the lower branches from growing but as long as the main shoot is intact it will be largely favored as the plant increases in height. By removing the main shoot, the branches beneath it become free to grow at full rate in order to take its place. Please note that when the top shot is removed, the plant will no longer continue to grow in that location, so you have to make sure that there are enough secondary shoots to make up for the loss.

The main shoot also has other functions. It communicates with photosensitive pigments located in the leaves. The information that these pigments receive dictates the behavior of the plant. Shoots on branches that are in the shade will be supplied with growth hormones in order to elongate and catch up with the rest and this might waste precious energy. I will explain more on this topic later on.

Flowering in plants is triggered by two things. The first part of the system is called the Circadian Rhythm, which is basically an internal biological clock. This biological clock is an evolutionary response to light and darkness and is tightly linked with hormonal functions in the plant. Certain things are supposed to trigger at certain times of the day but also at certain times of the year. The second part involves hormone signaling mechanisms, messenger molecules and specifically encoded proteins that tell the plant to start budding based on the information that it receives from the environment.

The plant knows when to trigger flowering because the sensory pigments in the leaves keep track of the photoperiod or the hours of daylight and relay this information to plant. The spectrum of the sunlight also changes with the seasons, which provides the plant with the information that it needs to trigger flowering.

The sensory pigments also inform the plant of how much sunlight a certain part of the plant receives, which enables it to relocate energy and growth hormones to where they are needed. Shoots that are stuck in the shade will elongate and that means building more stem. This energy could have been spent on other things, like bud nodes, which is why we try to help the plant to become more productive by topping and training it.

There are several types of hormones that regulate growth and behaviour. One of the most important growth hormones is called auxin. It originates in the main shoot and is part of a mechanism called the auxin transport system. This hormone plays a big part in the internal signaling and growth control mechanisms of the plant. It also regulates the formation and behavior of other growth hormones that are responsible for everything from root growth to the formation of flowers.

By removing the main shoot, the communication between the leaves and the main shoot ends, effectively canceling out the apical dominance. The result is that the plant assigns the next shoots in line to the job. This means that the smaller shoots on the branches beneath the cut start growing faster and gain size. Since there is no more apical dominance, the plant will grow into a bush because the newly appointed main shoots all have equal priority. These shoots usually grow very slowly when the plant is left untopped. The new main shoots will in turn suppress the shoots that are located further down on the main stem, so sometimes it is best to top the plant several times in order for it to fan out properly. Some say that it is best to top the plant at night when most of the hormones have been sent to the roots. This means that there is a smaller chance of the plant being stunted after the main shoot has been removed.
 

There will be a short period of time when the plant is in something that could be called a state of confusion. It will stop all activity until it can figure out what is going on. It will resume vegetative growth as soon as the hormonal functions are up and running again and the dominant shoots have been appointed. It should take no more than a few days for this to happen, a week at the most.

Most of the time this transition is quite fast but some plants that respond poorly to topping might display stunted growth for a while. It is possible to top a plant many times, each time the number of dominant shoots will double. Give your plants some time to grow before you top them. If they are topped too early they might get stunted for a while, mainly due to the loss of photosynthetic tissue. I do top them quite early sometimes as you can probably tell from the pictures that I have included. Go by your feelings, once the plants look strong enough you can start topping and training them. Look for secondary growth at the lower nodes, that usually means that it is safe to top the plant. When the plant has formed the fifth pair of leaves, it should be ok for you to remove the main shoot.
 

This is a good way of training the plant if one wants to make the most out of the space available. Topping is also a good way of slowing down plants that tend to stretch a lot as each time the plant is topped it will redirect energy to a greater number of dominant shoots. The new shoots will never grow as large as the untopped main shoot will but they will most likely yield more in total.

There is also a technique called FIM (Fuck I Missed) topping. By leaving a small portion of the growth on the main shoot intact, the plant will for some reason assume that four shoots, instead of two, are the dominant shoots and they will grow evenly in height. The success of this method is usually up to the luck of the draw but you should make the cut circular so that the remaining tissue forms a cup. Similar results can however be achieved by topping the plant twice.
 

Here are some plants in various stages of training.

Super Cropping

There is also a technique called super cropping, which involves the crushing of the soft inner tissue of the stem. This technique will allow you to gain some control over the plant, but it is mainly used to increase health, potency and yields. This soft inner tissue is made up of cellulose and forms a network of vascular tissue that can be divided into two groups; namely the xylem and phloem. These two are responsible for the transport of water and nutrients along the stem.
 

Breaking the plant's inner walls will cause it to rebuild. The plant will rebuild the tissue stronger than before and this is why this technique can increase the harvest. While rebuilding the tissue the plant expands on the cellulose network, which is why the stem grows thicker than before at the point where it was crushed. This allows for a greater transport of water and nutrients, which will directly affect the yield.

Think of it this way; instead of having a two way street for water and nutrient transport, you now have a multi-laned super highway.

If you pinch the main stem it will grow very thick, which will benefit the entire plant. Pinching the side branches will allow you to have more control over how she takes shape. Thanks to the bend on the newly crushed branch you can now redirect it in any way that you see fit. This will also allow more light to reach the lower buds. Since the branch will grow stronger at the breaking point, it will also be able to support more weight. The branches that are closest to the breaking point will also grow stronger in order to compensate for the injury.

The idea here is to gain some control over the shape of the plant while improving on health and increasing her yield. Pinched plants usually grow into very healthy bushes with thick stems and branches. Super cropping is also a good way of getting several main colas. The pinched branches will eventually grow so thick that the plant will treat them as if they were dominant shoots instead of secondary branches.

Super cropping should be carried out during the second or third week of vegetative growth. Take a branch between your forefinger and thumb and proceed to pinch and twist at the same time until you feel the insides start to collapse under the pressure of your fingers. Slowly squeeze and bend the stem without snapping it. Just squeeze lightly until you feel the branch give, then let go. The branch might droop for a while but that's ok as it will heal over time.

Keep in mind that sometimes you will have to keep the plant in a vegetative state slightly longer than usual as it takes the plant some time to repair the broken tissue and redirect energy. Plants are quite good at repairing these kinds of injuries, so there is no need to worry. In the end the plant will grow very strong and healthy. You might have to provide the pinched branches with some kind of support until they heal or the angle might become too extreme. Regular string will work just fine.

Topping and super cropping both serve the same purpose, the difference being that when you super crop a plant, you don't actually remove anything from it, you just bend it out of the way. The plant will however behave in a similar way because the main shoot is now located lower down than the secondary shoots. The result is that the plant sends up the secondary shoots as if the main shoot was actually removed. The secondary shoots can in turn be pinched and the effect is shifted towards shoots that are located further down on the stem. You will end up with a relatively even canopy which is good because then all the shoots will receive an equal amount of light.

Topping and super cropping should be considered mutually exclusive but a number of the other techniques can be used to further improve on the yield.

If this technique is applied correctly and with patience, the outcome will most likely be a stronger, bushier plant and a greater number of main shoots. The procedure can be repeated several times during the vegetative stage for even better results. I would like to point out that the vegetative stage is not set within a certain time frame. You can extend it as far as you like in order to have more time to shape the plant. Most plants won't start flowering until they are put under a 12/12 light schedule. I usually wait at least until I see preflowers before I put the plants into flowering stage, this also gives me enough time to work with the plants.

Low Stress Training (LST)

Topping the plant or Super Cropping it can be considered High Stress Training (HST), which might upset the plant to some degree. There is however another option called LST or Low Stress Training.

Topping and low stress training work quite well together but it's not necessary to top the plant in order to start the training. Some people prefer to leave the plant untopped and tie down the main shoot at ground level instead. This will have the same effect as topping it because once again, the centre for growth control located in the main shoot will dictate how the plant takes shape. When the main shoot is tied down, all shoots above it will grow more rapidly as the plant now assumes that the main shoot is gone.

These diagrams, originally posted by big_buddha, illustrate what I am talking about. These are excellent diagrams so many thanks to the creator.

It is possible to keep tying down each new branch as it pops up, which will result in a plant that grows into a dense bush with an even canopy. LST training combined with topping can be a very effective way of creating a plant that makes use of all the available space. If there is enough time for it, top the plant several times and keep the internodes as short as possible by bringing the light in closer. More nodes means more bud and less stem means less energy wasted. Training the plant in this manner takes some time and there is no way to reach good results by being in a hurry. As you can see, the plant in this picture has been both extensively topped and trained. If you look closely you can see where the branches have been tied to the pot. Tying down the branches in a circular fashion will help the plant to take on the desired shape.
 

There are many ways to train a plant and each plant requires a slightly different treatment. The goal is however to get a plant that looks like the one in the picture above. Once that plant goes into flowering it will have numerous shoots with many nodes. You can probably see what I mean. Once the bush gains size and starts to stretch, you will have to start pruning it carefully and wisely.

Just to demonstrate how many different ways a plant can be trained, here are some pictures of plants in early training. All of them were topped first. By training a plant you can also slow down the stretch, especially in pure or sativa dominant plants that tend to stretch more than indicas.
 

This Oldtimer’s Haze was stretching a lot and had quite long internodes so I topped it and trained it to grow around itself and eventually it grew into a sphere.

This Kali Mist plant was stretching for the light but did not like to be topped so I tried to slow it down by tying down the branches horizontally. In the end this plant preferred a few main colas so I stopped the training shortly after. Some plants will resist any attempts of training and respond poorly when you try. These plants will probably yield more when left untopped.

Here is an example of Ingemar’s Punch that went through some serious LST training. This plant resembles a creeper vine more than a bush. Here the goal was to keep the plant as low as possible but usually the plant is allowed to grow in size and height so that it produces a larger crop. This example however illustrates the possibilities when it comes to training. Remember that even if your grow room is limited in height, you are not restricted to growing solely Lowryders or other strains that stay low and small, as any plant can be trained to grow in any manner or shape. This opens up possibilities for stealthy cab and pc grows. You just have to reserve some time for the training during veg and perhaps you will have to continue the training during flowering as well, like in the example above. Anything is possible.

Scrogging, or Screen of Green means that you suspend a net over the plants and allow them to grow through it. This makes it easier to separate the growing branches so that they eventually cover the entire area of the grow room. The Scrog net also provides support as the buds can often become so heavy that that the branches cannot support them anymore and break under the weight. Thereby the Scrog net also removes the need for noisy fans, used to make the stems stronger through the waving effect. Personally never use fans due to limited space. If you can keep the temps within optimal levels, you don't really need them. The added support from the scrog net usually becomes necessary at this stage because the branches can be quite thin compared to the bud that they are packing.

I usually train the plants for up to two months before flipping the switch, which means that they are thick stemmed and quite large in size. If you can arrange for a separate vegging and flowering area, you can start training plants in one room while the others happily flower away in the other. Although plants can be kept very low with training, my aim is to grow large and busy plants that produce the maximum amount of bud. Due to the long vegetative period, the plants are strong and healthy with an abundance of bud sites. Keep in mind that the plant also stores up energy in the leaves. This energy will then be used during the flowering stage to produce bud. Naturally, the plant continues to feed on the nutrients in the soil but the energy reserves ensure that your plant will maximize its yield.

I try to keep the canopy even by topping the plants that stretch more but sometimes that's impossible, especially when growing both indicas and sativas at the same time. One has to make adjustments according to the needs of the plants and direct longer branches to the corners of the grow room. Different plant require different training. Sometimes the only option is to bend down and tie the branches horizontally so that they are resting on the Scrog net. This can be a strange sight as the flowers keep growing vertically out of the side of the bud.

Sea of green or SOG is the method of growing where a multitude of smaller plants are grown instead of few large ones. These smaller plants will mature faster and in less time than larger plants and one crop can be started while another is maturing. This saves the grower a lot of time and money as less time is required between crops. This method is also good for those wanting to make the most out of their smaller grow area.

Although SOG is more of a style of growing than an actual technique that can be applied in order to increase the harvest. I still wanted to mention it here as this method of growing will under the right conditions actually increase the harvest. As opposed to growing a few larger plants in the same area, that is. Since you want the buds to cover as much of the grow area as possible, 1-4 plants per sq. ft. is a good rule of thumb for SOG. More light in the grow room also allows for more plants.

The SOG plants do not require any training as that will only slow them down and delay the harvest. It is probably better to just grow more plants instead and fill out the entire surface area with as many plants as possible. In case the smaller plants do not fill up the entire area of the grow room, some minor LST training might be needed in order for them to branch out a bit more.

The SOG grow can also be Scrogged for further control over the plants. In order for this method to be truly effective, all the new plants would have to be clones from the same mother. That means that all the little plants will grow at the same rate, which is important for keeping an even canopy.

Although no topping and training is needed when growing SOG, the trimming of branches and fan leaves, especially lower ones, becomes a must because every little bit of space counts towards the harvest. By removing excess fan leaves that would otherwise block bud sites, the SOG grower improves on his yield. Since SOG grows usually contain a great number of plants in a relatively small area, the need for trimming fan leaves becomes apparent. After all, what we are after is a bountiful harvest and different methods apply to different styles of growing.

Monster Cropping or Flowering Clones is another method of growing that was brought to my attention by one of our members; JWP, who also was kind enough to provide the pictures for this part of the guide. This method involves taking clones of flowering plants and then forcing them to root and re-veg, which eventually leads to very bushy plants with a great number of branches and nodes. I named this technique Monster Cropping because that is what you will get, real monster plants, but also because this method was introduced to the scene by a grower named greenmonster714. He in turn credits a grower named Feral for discovering this technique.

You start by taking clones of a plant that is about 21 days into flowering. This seems to be the best time to do it but you can also take clones at a later stage with similar results. The lower branches make better clones as they have not yet become rigid and will also root faster and more easily than say the top cola. Move the new cutting into a glass of water and let it sit for a while in order to make sure that no air gets into the vascular system during handling, as this can be fatal to your new plant. You should make the cut so that it runs along the stem as this will increase the surface area for water and possibly nutrient uptake, depending on what method of cloning you use. Personally, I have found that using a small hydroponic setup or a propagation bubbler to be by far the best way to clone cannabis plants. I will not expand on the subject of cloning here, if you need more information on how to clone your plants, have a look at the official cloning thread by JJScorpio

In the picture below, you can see how the clone from a flowering plant been has placed in a propagation bubbler for rooting and re-vegging. This also means that you will have to put the clone back under a veg light schedule of 20/4 or even 24/0. Any less and the clone might just continue flowering. Clones do not need strong light so a small CFL will do. You can remove some of the buds and leaves at this stage in order to encourage the plant to revert back into its vegetative cycle but leave the topmost shoot alone.

It will take several weeks for the clone to root, some never do, so it is best that you take a great number of clones at the same time in order to ensure that at least one makes it on to the next stage. It might be a good idea to place the clones inside a humidity dome, which can be bought at gardening stores or custom built for your specific needs. The high humidity inside the dome will make sure that the plants do not dry out and die. Ventilate the dome every day just to make sure that the plants don't get attacked by mold.

As you can see, this plant has grown into a real monster, and all this without ever topping the plant. That's the beauty of this technique; you can forget all about topping and FIM'ing since the flowering clone will sprout all these new branches all by itself.

This plant is now perfectly suited for a SCROG or perhaps even a SOG grow. This one plant can easily fill up an entire Scrog net in no time. Several of these plants grown in SOG will definitely give you a grand harvest.

There are other benefits from using this technique; it also removes the need for keeping mother plants. When the newly re-vegged plant is flowered, it can also provide more clones for a perpetual harvest. Recycling at its best. This might be of interest to those who need to keep down their number of plants.

Needless to say, this method is highly effective thanks to the heavy branching that occurs after a flowering clone is re-vegged. With further training and some patience, you will get some real monster plants and thereby also a monster harvest.

When the plant is left to grow as it chooses, it usually has more branches than it has the energy to support. This means that a lot of energy is wasted on smaller branches, especially the lower ones. The energy need is spread out over so much growth, that in extreme cases flowering takes a very long time as the plant tries to supply energy evenly to every location. By removing some of the less important and weaker branches, you can ensure that the larger branches produce a greater amount of high quality bud. As some of the branches are removed, more energy becomes available to the plant. The bud on the lower branches that receive less light usually end up as single “pop corn” buds that never truly mature, so it is best to remove them at an early stage. These branches also have a tendency to stretch for the light and that results in fewer buds because a lot of energy is wasted on building stems.

You become the investment planner for you plants. Observe the growth and remove any branch that has long internodes (the space between the nodes) and any branch that stays significantly lower than the main shoots. These branches will get very little light and they will also have a hard time finding their way up to the well lit area. Most of the time I end up removing almost all the growth underneath the Scrog net, I only leave the fan leaves intact until the plant drops them by itself after the energy has been recovered. Leaves will go yellow naturally during the grow, when the energy is needed elsewhere. This starts at the bottom and moves its way up during flowering. There is no need for concern unless the top leaves are yellowing first or lose vigour too early.

When it comes to removing leaf material opinions vary, some remove leaves and others, like myself, chose not to. I have tried both methods and can honestly say that there is no positive effect really from removing leaves. Some say that defoliation gives you more bud but I have observed thicker, heavier and healthier buds when I leave the "solar panels" alone. Keep in mind that fan leaves are the primary location for photosynthesis and that the plant also stores surplus energy in them. By removing the leaves you do double harm; you handicap the plants ability to produce vital energy and you also remove the energy that has already been stored for future use. Furthermore, although it cannot be observed with the naked eye, some light actually passes through the leaves and that is why some of the lower growth stays green throughout the entire grow. It is better to tuck or tie the leaves under the canopy so that light reaches more bud sites, or alternatively cut the leaves in half.

Another thing to keep in mind is that there is a hormonal response in plants to being wounded. This includes a growth inhibitor called jasmonic acid. It tells the plant to favor defense over growth. The more you remove at any given time, the greater the response. This translates into stunted growth in extreme cases. It is therefore wise to trim the plants gradually throughout flowering, instead of removing all the growth at once. This hormone also plays a part in regulating the formation of trichomes, and that is probably why a little bit of stress is thought to increase potency. There is however a difference between stress and torture, a healthy plant will always produce more bud than a plant that has been severely handicapped.

Since most of the photosynthetic activity takes place in the leaves, the buds themselves do not need light. The primary function of the floral structures is to produce seeds, not photosynthesize. The smaller leaves on the bud provide them with energy locally but for the most part it's the larger fan leaves that supply the plant with energy, especially the roots. The larger fan leaves have the greatest surface area and also the greatest concentration of chloroplasts, which are small cell structures that contain chlorophyll, and we all know that plants use chlorophyll to capture sunlight. It is however important that the lower shoots receive some light or the plant will start to elongate the branches, which results in fewer nodes and longer internodes. This is counterproductive since we want as much bud as possible. This is where a Scrog net comes in handy, you can redirect the branches and tie down the leaves without removing them and thereby allow more light to reach the lower buds while no energy is lost.

Sometimes you do not have a choice and must remove some of the growth in order to ensure that you get a good harvest. It all depends, some plants respond well to rigorous pruning but in general I would advice that you keep it to a minimum since there are optional methods to removing the leaves altogether. The rules of pruning are a bit different when it comes to SOG grows as you might have to remove some of the fan leaves because the plants are packed so close together, shading each other.

Jump to...

How to grow short, bushy plants - several techniques

Defoliation: Controversial Technique to Increase Yields

Supercropping: Simple Secret for Total Plant Control

Low Stress Training (LST) Guide