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A Beginner’s Guide To Controlling Marijuana Plant Growth

Growing marijuana indoors isn’t always an easy thing to do. There are a lot of things that you have to contend with, but space is one of the biggest problems that people face. Marijuana plants tend to start stretching out and quickly filling up the small indoor grow rooms that people use. If you are going to overcome that, you will have to learn how to train and trim your plants in the right way, or else you will end up causing more problems that you are solving. At the end of the day, you’ll end up with far larger harvests and a much easier time throughout the growth.

Why Train Your Plants?

There are a lot of reasons to train your plants. Training your plants in the right way will drastically enhance the kind of results you have, primarily through:

Making Better Use Of Light

Light is the single most important thing that you are going to provide your plants with. After all, light is what makes the change between vegetation and flowering. When you train your plants, they will be better able to use all of the light that you are giving them.

When you grow plants in the traditional way, you are going to have a lot of leaves growing around the buds, sometimes even blocking the light that they should be receiving. When you have trained the leaves out of the way, your buds are going to be soaking up all of the rays of light that you throw at them. As you’ll see come up time and time again, the more light that goes directly to the buds the larger and more profitable your harvest will be.

Create Larger Yields

The one thing that is consistent among every person that trains and prunes their plants is that they have a much higher yield than people that grow using the traditional methods. At the end of the day, that’s what it is all about, right?

This is accomplished through the simple fact that you are going to be cramming your grow space full of nothing but buds. Training your plants to grow in the right way, or trimming them properly, you’ll create fields of buds without all of the excess leaves that are only taking away from the amount of energy that is supposed to be going to flowering. The more energy that is spent on growing buds, the larger they will be.

The Right Conditions For Controlling Growth Indoors

Before you start trimming and training your plants, you’ll have to be sure that you are providing your plants with the right conditions. Without having the right area to grow in, your plants aren’t going to be able to thrive in the new position that you have put them in. That is why it is so important to have the right strain, give them the right kind of light, use the proper container, keep the temperature right, and give them plenty of air circulation.

Have The Right Strain

Before you even start growing it is important to have the right strain for the indoor conditions that you are growing in. Depending on what you are looking for, you probably already have a few in mind, but it is important to know what you are getting into before you plant them.

Sativas have the signature “up” high that a lot of people look for during the day, but it can become a problem when you are growing it indoors. Sativa plants can double, or even triple in size, during the flowering phase. This means that you are going to run into serious size issues if you have a small indoor grow that you are using. This is when training and trimming is especially important, since it eliminates the problem, although it can be a bit more work depending on the amount of room that you have available.

Indicas, on the other hand, are known for being short and bushy plants naturally. These strains will have more of a pain killing and sedating high, which many people are looking for. It might seem like this wouldn’t require training, but if you want the absolute largest amount of buds, training is still going to be important.

There are also autoflowering strains to think about. These kinds of seeds are going to automatically start flowering after a few weeks, thanks to technological advancements in genetics, but this can be an issue when you are trying to train your plants. They are available in both indica and sativa varieties, but not having the opportunity to allow them the right kind of growth before they start budding will severely limit the kind of training that you can do. If you have plenty of room to grow in, these are great hands off type strains. If you are limited on space, however, you might need to look elsewhere.

With all of this being said, it is still important to think about what you are looking to get out of the strain. Do you have particular characteristics you are looking for? If you are tight on space, you might still want to have an energetic high instead of a sedating one. You might also have plenty of room and still want to grow a great painkilling strand. Think about what you are looking for, since you shouldn’t make sacrifices on the finished product just because one might be easier to train than others.

Provide The Right Amount of Light

Light is what gives your plants life. Without it your plants are going to die, but when you are placing stress on your plants through training it is even more important that you ensure proper light levels inside of your grow room.

In general, more light is going to lead to bigger yields anyway. When you have light taken care of, you’ll have large harvests, but when you combine that with training and trimming techniques you’ll have larger harvests than ever. There is a problem that comes up, though, when you try to blast your plants with too much light using lights that heat up to incredible temperatures.

That is why you should be using LED grow lights if you are going to be training your plants. These will give your plants the right amount of light. Without plenty of light, they will start to stretch up higher than ever in order to reach the light source, which will lead to you quickly running out of room inside of the grow space. Giving your plants strong LED light is going to automatically make them smaller.

LED lights will also be very helpful in that they don’t produce much heat. This keeps your grow room much cooler during the light periods, which is healthy for them, but it also helps in another way that we will get in to later.

It should probably go without saying, but make sure that you have enough lights to cover the entire canopy once you have started training and trimming your plants. Having a strong LED light in the center might be great for some forms of growing that involve a single cola, but if you are growing an entire canopy of buds you will begin running into problems.

Use The Right Size Container

When you train and trim your plants, you are going to be creating a plant that is much heavier than anything that would naturally grow on its own. That makes the roots even more important than normal, which is why you have to have the right sized container for the task at hand.

If the container that you are using is too small, the roots aren’t going to have room to stretch out. On the other hand, too large of a space will also lead to problems during the right amount of nutrients.

Here is a quick rundown of the size of containers that you should be using:

For 12 inch tall plants indoors One 2gal container for each plant
For 24 inch tall plants indoors One 4gal container for each plant
For 36 inch tall plants indoors One 6gal container for each plant
For 48 inch tall plants indoors One 8gal container for each plant
For every additional 12 inches in height Add 2gal to the size of the container for each plant

A Note On Temperature

The temperature of your grow room can be the difference between success and failure. It is also one of the hardest things for some people to control depending on the kind of lights that they are using. Once you have the temperature under control, though, you can start to fine tune it in a way that will make training much easier on your plants and help you along in the process.

The temperature during the vegetative stage should be between 70 and 85 degrees. For flowering it will need to be between 65 and 80 degrees. What is important for our purposes here is that the temperature during the light and the dark periods should be very close. Making the two temperatures as close as possible can help drastically slow down the stretch that sativas especially are known for experiencing.

There are a number of ways of accomplishing this, but it will largely depend on the kind of grow room that you have and the temperature that it is naturally at. If the days are too hot, cool them down with more air so that it matches the dark period more closely. In some colder climates, you might have to actually warm up the room in the dark periods, although that isn’t going to be a very common practice. In most cases, if you have to warm up the dark periods, it will only be around five degrees or so. Warming up the plants too much can cause problems in the long run.

Provide Enough Circulation

Before we move on to covering the kinds of training options that are available to you, it is important to cover circulation a bit. It should go without saying that you need a large amount of air to be moving in and out of your grow room, but this can also have a large impact on the kind of success that you have with your training and trimming.

First, proper air circulation is important when you have trained your plants to grow into a large canopy. This can slow down the movement of air and can lead to moisture issues that can kill your plants. With enough air circulation they will be able to breathe and stay healthy.

It is also important because, in nature, plants are going to be hit with breezes and air currents that attempt to push them over. That kind of stress will help build their stalks into strong, durable bases for your plants to grow on. This is always important to plants, but when you are growing a plant that relies heavily on buds it is even more vital. Training will cause your plants to grow out horizontally and, while they will be supported by a screen if you use a Screen of Green system for example, it will still place a lot of pressure on the main stalk of your plants. If you don’t make sure that the plants are strong enough, they are going to have to spend a lot of energy just staying alive instead of growing buds, which reduces the harvest and as a result your profits.

This means that you cannot only rely on an exhaust fan to circulate air. When you are growing with any kind of training during the vegetative phase, place an oscillating fan on the ground so that it will help strengthen your plants at a time when it is most crucial. The wind doesn’t have to be strong enough to blow your plants over, but it should be enough to give them a slight stress while they start to expand through the vegetative phase.

Training Plants

Training plants is the most tried and true way of getting larger harvests in a small amount of space. With the right kind of work put in to training them during the vegetative stage, you are going to have plants that will never get out of control indoors, but also be more fruitful than they have ever been.

Low Stress Training

There are a lot of ways to train your marijuana plants to grow a certain way, but many of them rely on physically attaching them to something that is set in place. Low stress training, in contrast, simply involves pulling the plants into the right shape over time, using anything from pipe cleaners to strings and wire.

The idea here is that you are going to wait until your plants have several healthy branches growing in an upward direction, and then pulling them downward, backward, and out. Once you have pulled them down, you can attach strings to them. Over time, you can begin to gradually increase the tension as the plant grows, training the plant to be in the perfect shape for growing in small spaces.

The ideal way to do this is to attach two strings to a rubber band. This way, you will constantly be applying pressure to the branch, even as it grows used to being held down. You should always focus on that: consistent pressure. You don’t want to force them down in a way that will shock them, but you do want to gradually pull them into place.

If you have already started growing and have noticed that your plants are starting to grow too tall, this can be a way of solving that. This is especially true if some of the plants are growing taller than others. You should always have as even of a canopy as possible, so Low Stress Training can be used to fine tune your growth as it moves through the vegetative phase.

It is important to note here that this is virtually the only way to train autoflowering plants. This makes sure that they train over time, which is perfect since you won’t have to wait for them to fill out any other space, as you will with ScOG training methods, for example.


Screen of Green, or ScrOG, is one of the most popular ways of training a plant. You will essentially be ensuring that your plants have an even canopy that stretches out to fill the grow room horizontally, while also encouraging the right kind of growth that will produce the most buds.

First, you will need a screen with holes that are around 2 inches square. This can be chicken wire, netting for a garden, or something that you have created your self. It should be sturdy enough to support rapidly growing plants.

Next you will be placing the screen between eight and twelve inches above the growing medium that you are using. This will not only give you enough space to work with the plants underneath, but it will also let the plants begin to grow a strong base before they are trained against the screen.

As your plants grow above the screen, you will start pulling the branches back down and tucking them under the screen. The goal is to fill out the space as much as possible, so just keep directing the branches towards the outer edge of the screen.

As the plants grow, you are going to have to make sure that you have plenty of light going to the canopy, as well as plenty of air circulation under the canopy. When you block off a part of the room with a canopy like this, moisture can start to build up.

This is one of the best things that you can do for sativa strands, although indicas can also flourish in this environment. The end result is a room completely filled with healthy plants and massive buds.


Sea of Green grows, despite the fact that they share a similar name with Screen of Green, is another topic entirely. This is something common with the Dutch, but not too many people have used it in comparison to other training methods.

You are going to be training your plants to grow close together, but they are also going to be forced into flowering early.

Each plant should have about one square foot of space to grow in. Plant as many as possible inside of the space that you have available, although you should always make sure that you have plenty of room to move inside of your grow room.

As the plants start to grow closer together and sprout buds, they will create a canopy. The lower branches are going to suck up energy, but they aren’t going to be able to do much for the plants and they will likely eventually die. It is recommended that you trim the lower branches off once they stop receiving light in order to help your plant spend more energy growing buds instead.

This can take more effort than other types of training plants, since you have to keep a constant eye on whether or not everything is receiving the ideal amount of light, but that doesn’t mean that it won’t pay off in the end if done right.


Supercropping seems like a barbaric thing to do, but it results in extremely strong branches thanks to the miracle of biology. This technique can make your plants healthier and increase the yields. Basically, you are going to gently breaking the inner tissues of the stem and convincing the plant that it should grow stronger and in the direction that you would like.

After three or four weeks of vegetative growth, the plants are going to be ready for supercropping. You will need to choose a point on the plant, typically around the first and third sets of nodes, that you are going to pinch on each plant across the grow room. Simply squeeze the plant and bend it at a 90 degree angle. Be careful to not break the branch entirely, but it should be easy to fold the branch over horizontally. As the plant starts to repair itself, you will once again break all of the plants at the same place, so that they learn to start growing at that angle, producing buds that grow straight up.

When you train plants with wire, for example, it can grow horizontally, but the plants will still be relatively weak. With supercropping, however, the plants will be incredibly strong and capable of supporting massive harvests. You may end up needing to leave them in the vegetative state for longer than normal, if that is what it takes to heal completely, but once you start flowering all of that work is going to pay off in a big way.

Trimming and Cropping

Training plants is often combined with a method of trimming your plants so that they grow more buds automatically. You can, of course, trim your plants into the right shape and have larger harvests on their own, but it is best to use them with another technique.


Topping continues to be one of the most misunderstood ways of cropping a marijuana plant to get bigger yields. In general, a plant is going to grow a very large cola on each branch, but with topping you can create a plant that has several large colas that absorb all of the light and grow larger than ever. These will be smaller colas overall, but the number will make the yield much larger.

It is important to start doing this early on in the vegetative stage, so that each offshoot can grow as large and strong as possible. This is important, since usually the main shoot is what is going to hold the most weight. With topping, however, you are going to be removing that main shoot.

To top your plants, look at the tallest shoot of the plant and cut it below the last node that has fully developed. This will instantly reduce the height of your plant, but it will also create a plant that grows in a bush like fashion.

This will add a bit of time to the vegetative stage of growth, but only an extra week or so. Indicas can sometimes take much longer, although that isn’t always the case. When done properly, topping can create massive harvests that are almost all large buds, rather than filled with leaves that you aren’t going to be able to use for much of anything.


FIM trimming will help create four main colas that buds are going to grow off of. This is typically combined with training methods, like main-lining will be, but the trimming is the most important part.

You have the option to either physically cut or simply pinch it off. These can both work well, although cutting is usually the best way to go when it comes to doing anything that can place stress on your plant. With that being said, pinching can be more forgiving if you haven’t done this before.

Once the plants have grown between three and five nodes, you will be ready to FIM them. Push the leaves at the top of the plant apart and you will see a small leaf bud beginning to grow. Take off about 75 percent of that and it will tell the plant to grow up to four new colas where it was once growing one.

This is very similar to topping, with the only real difference being how much you are taking off of a plant. With the right attention paid to them, the results will be large and incredibly profitable.


Main-lining marijuana plants is a relatively new concept to growers. There are not a large number of growers using it, but those that have perfected it are starting to see incredible results in the form of massive harvests. Basically, you are going to be cutting your plants three times and creating a “manifold” of massive buds.

First, you are going to create two main colas on your plant. Let the plants grow around six nodes and then top them at the third node. This will give you two colas.

Once those new colas have grown between two and four nodes, you will top them to the first node. This leaves you with four colas.

If you want to, you can do this process over again when those colas have three nodes. This will leave you with eight colas that will grow into large buds. As always, though, you should clean up any extra growth that starts to happen if it is getting in the way of the plant’s light.

For the best results, you should also use Low Stress Training to get them into the right shape to fill the space and create a canopy. Refer to the guide above for help with that part.

Tips For Training

Don’t force flowering right away

Timing the flowering is important to having a successful harvest, but many people decide to force flowering far too early. Once you have topped or otherwise trimmed a plant, you’ll have to wait until it has healed enough to start flowering. If you begin cutting off the tops of colas late in the vegetative stage you will have plants that aren’t ready to flower yet. For the most part, waiting a week is going to be all that it takes to get started growing buds.

Only use sharp scissors

If you start using dull scissors, or try to just rip off the branches with your hands, you are going to start damaging the plants more than you are helping them. Keep a pair of sharp scissors on hand that you are only going to use for trimming your plants. Just any pair out of the drawer isn’t going to get the job done effectively. If you injure your plants you will have them sending energy to repairing themselves instead of continuing growth.

Get rid of the dead leaves

The larger a plant gets the larger of a canopy will form. That canopy is going to block out light to many of the other leaves that are on the plant, which will in turn kill some of the leaves. Once leaves have started turning yellow from a lack of light, it is best to trim them off, rather than trying to hope that the good leaves make up for the dead growths.

Cut out the low branches early

When your marijuana plants are still small, they will quickly recover if you trim off branches. This is the perfect time to begin trimming off some of the lower branches that aren’t going to do anything for the plant once it begins flowering. This helps support the taller branches and you will find that it is much stronger when it comes time to start flowering. Those small branches you cut off aren’t going to be good for anything at this stage, if you leave them there.

Don’t wait until flowering to start pruning

Once your plants have started flowering, you shouldn’t try to prune them any further. There are going to, of course, be dead leaves around that must be trimmed, but for the most part you should avoid it. During flowering the plants are going to be growing much faster than in the vegetative phase and any major change from pruning is going to give it a real shock that might harm it. Some people are going to say that stressing the plant makes it grow faster, but so far there is no evidence to support that.

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