This Tutorial will attempt to explain FIM pruning in a clear and more accurate way, and to improve upon (take the guess work out) the already notorious FIM technique. After reading all I could find on the subject, I was still left scratching my head, and unhappy with the results... so I figured I better get this info up, so others may benefit from my mistakes

FIM is performed in order to limit plant height and encourage lateral branching. This technique and others like it (SOG, SCROG, LST, Topping), are especially beneficial, when growing under artificial lighting, which has very limited penetration/capability. In other words it's good to keep your plant growth within the penetration area of your lamp. I believe FIMMing is preferable to topping, so reasons I'll go into later, but first a chart which shows the optimal penetration range for most HID lamps.


I've seen the other tutorials on FIM, and they all seem to be somewhat confusing, or downright inaccurate.

FIMMing isn't rocket science, it's pruning the growing tip of a plant - just as topping is - but do it wrong, and you'll soon know why they called it FIM (F*ck I Missed)

For clarification: Topping is the removal of the growing tip at or above the 2nd or 3rd visible node, whereas FIMMing is the removal of the uppermost growing tip above the uppermost visible node - this growing tip is only visible, and accessible, if you part the tender new fan leaves. Clean fingers, a knife point, or a pair tweezers works well for this.

Note: When doing plant surgery always start with clean hands, and sanitized equipment.

First let's look at what happens when you FIM incorrectly. When removing the top "80%" of the uppermost growing tip - as I've seen in some FAQ tutorials - you are likely to miss the growing tip entirely, and end up trimming your tender new fan leaves instead, and it's never a good idea to trim fan leaves! You can think of fan leaves as the plants solar panels; this is where the energy comes in, and the more energy in, the more bud out, hopefully.

In this first pic it's still unclear as to whether, or not, the growing tip was pruned out, or not, but what is clear is the fan leaves were pruned, and this is what you want to avoid - for obvious reasons.


In this second Pic you can clearly see the results of a failed FIM attempt, which, again, resulted in clipped fan leaves, and a growing tip that continued to grow. This plant was later re-FIMMed (properly), and LSTed.


The next Pic is the same plant in the second pic - properly FIMMEd and LSTed. As you can see this plant already has lots of branching, which will become the new tops. I'll try to get a better closeup of a successful FIMMing and have it up shortly... the tiny growing tip was removed, while leaving the precious fan leaves intact, and that's what constitutes a proper FIMMing.


This is a good graphical image, but again, where it says "FIMM cut location" is NOT where you want to cut! First you want to gently spread the tiny "new set of fan leaves" out of the way, find the actual growing tip, and then make then nip it out. Only then can you be sure you are pruning out the growing tip, while at the same time preserving the surrounding growth.


So lets recap:

1. Cleanliness

2. separate the new growth (fan leaves) using your fingers, knife tip, tweezers, or whatever works for you.

3. locate the growing tip - that would be the main stalk - ONLY- where it says to cut, in the above pic.

4. Now comes the FIM: Using a very small knife, scissors, or clean finger nails, carefully remove the growing tip, while being careful not to clip the surrounding growth. Be especially careful if attempting this with a razor blade, because they have a way of cutting through more than you intended.

I was able to find this pic, and doctor it, but again it shows the cut being made across the new fan leaves (wrong). In order to make the correct, more precise cut, you must first spread the leaves marked with the red X, and use a much smaller scissors... but this Pic does however show the growing tip we want to nip out (follow the red arrow).


Again don't make the cut as shown in the above Pic, go back and read the last paragraph (in green).

Remember, Just cutting through the uppermost growing tip is a crap shoot, at best, and you're liable to cut the new fan leaves, which isn't good.

FIM isn't much different than topping, but it's less drastic (stress), and leaves more auxin's, and more nodes. In my opinion FIM gives you more natural growth, and stronger branching, and it doesn't limit you to 2 tops as topping does. I also understand some people are getting 4 tops using the old topping technique, but to achieve that result, you need to top at a specific time, or node. There are no restrictions using FIM - to get multiple tops - other than the normal ones; never prune a seedling, or a plant in flower.

If I can manage to get a clear closeup Pic - of a proper FIMMING - I'll add it later, but from the feedback I've already received, it seems like everyone understands this (refined) FIM technique more clearly now.

OK I have the pics - as promised - but since I don't have an extra pair of hands, I'll have to explain what each one is:

This first pic shows the top we're gonna FIM:


In this pic I've gently moved some of the new growth out of the way, using my fingers:


In this pic you can see the actual growing tip we want to cut. A pen knife works great for this! Go slowly, and be gentle, because this tender new growth is extreemly easy to snap off, with only slight pressure! If you break a tiny fan leaf off, don't sweat it; you'll get better at this the more you do it, and you've still done less damage than you would using the old technique.


This Pic shows the growing tip - removed. If you look closely you will see the removed tip @ 1 o'clock. If I had come back later in the day to make the cut, I may been able to make an even more precise cut - because this growing tip is constantly changing shape - but I'm happy with the results:


The next 2 pics show the removed tip, as well as the scale we're working with here.


Here you can see how a V shaped cut might do an even better job, but we'll tackle microsurgery some other time LOL


Thanks for all the great comments,
If you have any questions feel free to ask away

__________________
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." - Thomas Jefferson my grow

Great!!! +rep.
One question, when is the best time to fim? Is it after the plant gets its first set of opposed leaves?

Nice thread mann.
I have never fimmed myself, only topped, and it worked out really great.So, if i fimm, do i get 2 tops or what???
Sorry, Im really baked right at the moment

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Oh, and that chart was fucking random...hehehehehe




Keep up the splendid work mate...

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Thanks buddy,

You can FIM any time in the plants growth cycle, except seedling or flower - for obvious reasons - but I'd say if you're having a hard time identifying the actual growth tip, wait until the next day and look again.

__________________
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." - Thomas Jefferson my grow

I should get baked, but I have too much to concentrate on right now

It's up to the plant how many tops... but they do branch out nicer, than when you just lop the top off.

To tell you the truth I have to do more experimentation before I can give an accurate number of tops to expect with this technique. It may also be strain dependant.

Once this thread gains some steam, we'll nail it down better.

__________________
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." - Thomas Jefferson my grow

this is by far the most clear explanation of fimming i've seen. thank you!! + rep

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So what your saying is that basically, this guy Just fimmed! has done it wrong?
I FIM almost every grow and would be interested to hear what you think the added benefits, apart from the obvious not damaging precious fan leaves, this technique offers as I have always just snipped straight accross the new growth and had great results!
Look forward to your reply............

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Yes I might talk alot, but that does mean that I have got, many green plants in many big pots or that I have a stinky, stealthy, badass crop!!

Thanks Stgen

Bobby9, i believe the guy in the picture could have done a cleaner job, and he's only guessing where the growing tip is.

I'm about to post some pics showing, exactly where the growing tip.

This technique is superior over cutting strait through all the new growth, because:

1. you can't miss (FIM stands for F*ck I missed) because there is no guesswork.

2. Less damage = less stress

If you can get better results than you're already getting, why not...?

__________________
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." - Thomas Jefferson my grow

OK I have these pics, and attached them to the tutorial on the first page

Since I don't have an extra pair of hands, I'll explain what each one is:

This first pic shows the top we're gonna FIM:


In this pic I've gently moved some of the new growth out of the way, using my fingers:


In this pic you can see the actual growing tip we want to cut. A pen knife works great for this! Go slowly, and be gentle, because this tender new growth is extreemly easy to snap off, with only slight pressure! If you break a tiny fan leaf off, don't sweat it; you'll get better at this the more you do it, and you've still done less damage than you would using the old technique.


This Pic shows the growing tip - removed. If you look closely you will see the removed tip @ 1 o'clock. If I had come back later in the day to make the cut, I may been able to make an even more precise cut - because this growing tip is constantly changing shape - but I'm happy with the results:


The next 2 pics show the removed tip, as well as the scale we're working with here.


Here you can see how a V shaped cut might do an even better job, but we'll tackle microsurgery some other time LOL


Thanks for all the great comments,
If you have any questions feel free to ask away

__________________
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." - Thomas Jefferson my grow