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Everything You Need To Know About LST/FIM/TOPPING

Discussion in 'General Marijuana Growing' started by growman3666, May 2, 2009.


    growman3666 Well-Known Member

    A complete guide to topping, training and pruning

    I will cover the basic idea behind topping the plant and how to apply the various techniques in combination for the best results. Keep in mind that this is only one method of growing and that there are many other ways to do it.


    Topping the plant means that you remove the main shoot located on the 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”.

    The reason why the plant behaves this way is because the center of growth control, the auxin transport system, is located in the main shoot apex. Sensory pigments in the leafs inform the plant of various things like how much light a leaf at a certain location gets and so on, which then enables the plant to transport energy and growth hormones to various areas.

    The mechanism behind the auxin transport system is quite complex, involving various messenger molecules, growth hormones and specific proteins that trigger everything from vegetative growth to flowering in the plant. Some aspects of this mechanism are still unknown and under scientific research. What is known however is that the centre of control for this mechanism is located in the main shoot apex and that it also relies on information from the sensory pigments located in the leafs.

    By removing the main shoot, the communication between the leafs and main shoot ends and the result is that the plant assigns the next shoots in line to the job. This means that the smaller shoots on the node beneath the cut starts growing faster and gain height. These shoots usually grow very slowly when the plant is left untopped.


    Most of the time this transition is quite fast but some plants that respond poorly to topping might have stunted growth for a while. It is possible to top a plant many times, each time the number of main shoots will double. Give your plants some time to grow before you top them, if they are topped to early they might get stunted for a while. I do top them quite early sometimes as you can probably tell from the pictures that I have included. Go by your feeling, once the plants look strong enough you can start topping and training them.


    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 shoots. The new shoots will never grow as large as the untopped main shoot will but they will most likely produce a larger crop.

    (Credit to the original creator of this picture)​

    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 main 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”. The same result can however be achieved by topping the plant twice.


    Here are some plants in various stages of training.​


    Topping the plant is only the first step in the process of training a plant for a super sized crop. After the plant has been topped many times over and starts to gain size, it is time to start training it.

    It is 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 auxin transport system located in the main shoot will dictate how the plant grows. When the main shoot is tied down, all shoots above it will grow more rapidly as the plant now assumes that these are the main shoots.


    Training the plant is this way is called Low Stress Training or LST. As long as the main shoot is kept lower than the surrounding branches, they will grow rapidly in height.

    These diagrams, originally posted by big_buddha, give a good picture of 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 grows, which will result in a plant that grows into a dense bush. LST training combined with topping can be a very effective way of creating a plant that makes use of all the available space. The trick here is to top the plant at each new node and to keep the internodes as short as possible. 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 topped and trained. If you look closely you can see where the branches have been tied to the pot.


    There are many ways to train a plant, 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 many branches 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 differently plants 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 tropical sativas.


    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 did not like to be topped so I tried to slow it down by tying down the branches vertically. 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 a Ingemar’s Punch plant 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, as any plant can be trained to grow in any manner or form. This opens up possibilities for stealthy cab and pc grows. All you have to to is 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 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 any more 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.

    I usually train the plants for up to three months before flipping the switch, which means that they are thick stemmed and quite large in size. Although plants can be kept very low with training, my aim is to grow large and busy plants that produce the maximum amount of buds. Due to the long vegetative period, the plants are strong and healthy with an abundance of bud sites.

    I try to keep the canopy even by topping the plants that stretch more but sometimes it is impossible, especially when growing both indicas and sativas at the same time. One has to adjust according to the plants and direct longer branches to the corners of the grow room, sometimes the only option is to tie the branches horizontally so that they are resting on the scrog net. This can be a strange sight as the buds keep growing vertically out of the side of the flower.

    The basic idea is that the training should be complete by the time the plants start flowering and grow through the net. Sometimes a second scrog net is necessary higher up if the plants need further support.

    There are also different methods when it comes to scrogging, some people tilt the net so that one side is higher than the other, as this provides a greater surface area for the buds.

    Some of the LST and other techniques mentioned here can also be applied to the "Sea of Green" or SOG method of growing, where many small plants are grown instead of a few larger ones for a quick and bountiful harvest. This method is a good alternative for smaller growrooms. Plants should not be topped when using the SOG method as the idea here is to harvest the main cola from a whole bunch of smaller plants and topping them will only slow them down. Although the smaller plants can be trained using these methods, it is probably better to just grow more plants instead for a maximized crop.



    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 so spread out 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. 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. 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 to find they 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 leafs intact until the plant drops them by itself after the energy has been recovered.

    When it comes to removing leaf material opinions vary, some remove leafs 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 leafs. Keep in mind that fan leafs are the primary location for photosynthesis and that the plant also stores surplus energy in them. By removing the leafs 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, light actually passes through the leafs and that is why some of the lower leafs stay green throughout the entire grow. It is better to tuck or tie the leafs under the canopy so that light reaches more bud sites, or alternatively cut the leafs in half. Since most of the photosynthetic activity takes place in the fan leafs, the buds themselves do not need light, in other words, bud sites are activated by light when it hits the node but the energy is produced and transported to the buds from the leafs. This is where a scrog net also comes in handy, you can tie down the leafs without removing them and thereby allow more light to reach the buds while no energy is lost.

    Topping and training is also a good way to keep mother plants from growing too large. There are several good threads on how to keep bonsai moms on this forum so I will not venture further into that topic.

    The combination of all the techniques described here always gives me the best result. I have tried growing plants in every possible manner, and topping, training and pruning produces the largest crops by far. All grow rooms are different and so are each strain of cannabis, in fact, every plant is different, so you will have to try out what works best for you but I hope that this guide at least gave you an idea of what my method is.

    blueberry1 Well-Known Member

    You are my mj angel!!!!! I was just wondering about fimming.....so thank you for this great thread!!!!!

    I am supercropping/lst-ing if you want to check out my thread last 2 pages have good pics showing up close the types of grow.

    Dogenzengi likes this.
    Sure Shot

    Sure Shot Well-Known Member

    Hats off to a great overall job!
    Dogenzengi and growman3666 like this.
    Where in the hell am I?

    Where in the hell am I? Well-Known Member

    Gr8 collaboration of works:clap:
    This shud help a lot of ppl through their adventures. +Rep if it'll let me!!
    And I'll rate yer thread w/5 stars, as well!
    Dogenzengi likes this.

    growman3666 Well-Known Member

    Glad to help out :)

    marni3d Well-Known Member

    wicked - i might just go an top one of my plants now - thanks
    Dogenzengi likes this.

    growman3666 Well-Known Member

    let me know how it goes

    dynamitejack Well-Known Member

    Thanks you answered alot of questions I had. +rep
    Dogenzengi likes this.

    anthony6216 Active Member

    Good pics I like your walk through!

    Peace and 1love,

    futbol.madrid07 Active Member

    Def a good explanation...believe me those diagrams always work wonders hah thanks bro
    Dogenzengi likes this.

    slipperyP Well-Known Member

    How does this look....does this cut need to be lower? Nothing teaches like experience. I cant wait for this to grow out.
    Top 44

    Top 44 Well-Known Member

    Thanks for the info
    Dogenzengi likes this.

    growman3666 Well-Known Member

    Looks like from what i can teel of the picture that you got it correct

    blueberry1 Well-Known Member

    Hey Growman, I thought I could just put a couple pics in here...Does it seem like my plants are too big to be topping now...? I have a couple supercropped which are 47 days old now (like 20 inches if left to grow vertically), most plants are LST'ed and are about 10-15 inches tall, and plan to SCROG. I feel like I could start flowering in 1-2 weeks cuz they are getting huge.

    oh crap, this pic is like 5 days old. All their leaves are touching/overlapping now (about 65% filled in Sea of Green), and they are a few inches bigger/wider than this pic.....

    Based on all that, if you'd like, let me know any thoughts and thanks again!

    Attached Files:


    Intuition Well-Known Member

    Dude all the information posted on here is bullshit. Thats not the way to do it

    Just kidding. That was a really good post. Think ill try scrog next time but lst is the shit and ftw
    Dogenzengi likes this.

    blueberry1 Well-Known Member

    Haha..intuition i was about to say something.......even tho i'm a beginner it seems like a great thread. ahahaha

    yeah yeah this is great i will probably do topping next time. The scrog is gonna be fun to weave those babies thru the screens...
    Dogenzengi likes this.

    Purple^stars Well-Known Member


    Shackleford.R Well-Known Member

    kiss-ass We're not worthy kiss-ass
    kiss-ass We're not worthy kiss-ass

    Incredible source of information, I will definitely be using this guide to train my plants. Check my grow in my signature, this is exactly what I was looking for.

    Dogenzengi likes this.

    Shackleford.R Well-Known Member

    I managed to get 5 out of 10 bagseeds to germ, and they are growing pretty strong. For a whole list of reasons I'm growing all 5 plants in one GH WaterFarm unit. Once I start to see sex, I plan on removing males, and leaving the females to strut their stuff (if my calculations are correct I have 5 females :hump: i wish...)
    I attached some photos to give you an idea of my grow as it is right now. Im considering topping, then LST, and ultimately SCROG. what do you think, o training guru?

    if you want to check out my grow, the link is in my signature.

    :peace: and keep :joint:

    Attached Files:


    growman3666 Well-Known Member

    If you a plant to lst then i reccomend topping at the same time,
    topping sets off a hormone that tells the plant it needs to start producing inner growth and fast, the lst will be more effective and you will have two more tops to boot :)
    Dogenzengi likes this.

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