Topping and SCROG for Sour Diesel Auto?


I’m new to this so looking for advice. Last fall, I grew my first plant, a Northern Lights Auto on a small grow tent (2’ x 2’ x 4’ or 60 x 60 x 120 cm). I used a bubble hydro setup and Fox Farms nutes. I have a 320w LED grow lamp in the tent and had it in my basement where the temp was 66-69F (19-20C) and humidity controlled at about 40% I got a decent result, but feel it was sub optimal.

I am germinating seeds right now for my next grow - Sour D autoflower (purchased from ILGM!). I have read all kinds of blogs, tutorials and grow journals about topping and SCROG to improve yields. I have read just as many that say you should not do this with autoflowers.

So, should I top my Sour D plant and attempt a scrog? If so, when to cut, and how far above the plant should the screen be?

Eternally grateful,

Wake up to Find out, you are the eyes of the world…

@Eyes_of_the_World welcome to the forum. Do not top your auto Fim it and LST the plant. Let me tag a few growers @SKORPION @Covertgrower @Nicky

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What kind of light do you have exactly. Lighting is the most important part of a grow set up. You can top, or fim and you can lst or scrog. But just reading your post I bet just better lighting will make the most significant change in the yield.


Welcome ILGM. Yes they can improve the yields, but if you don’t have a light to support it, it won’t yield more.

I also recommend low stress training instead of topping an auto. But people still top.

Screen Shot 2020-07-07 at 10.25.27 PM

This is my light.

So what is the difference between FIM and LST? I thought SCROG was a form of LST? I’m getting really confused here. I have too many acronyms running around my head.

More importantly, what is the best plan for my soon-to-be Sour Diesel seedling? I started germination two days ago in Rapid Rooter plugs. Looks like I may have a leaf tomorrow or the next day.

My understanding of SCROG is that one cuts the main branch early in the grow cycle, forcing the plant to grow two forks instead of the main line. Then, the branches are trained horizontally so the flowers come out the top of the screen and flourish due to extra light. The big, difficult part of this for me is the idea of cutting off the main branch in an autoflower that will only have 70-80 days to harvest. I value all input, and am particularly interested to hear from folks who have grown Sour D.

FWIW, I am probably a little too anal retentive / OCD to be growing weed. I need it for just that reason and I am open to feedback. :wink:

Finally, please do something today that improves someone else’s life. It is as big of a game changer as gratitude. Trust me.

Thank you,

The Eyes of the World

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Yep need a new light you will never get the yield you want with a cheap blurple light. Your light is a 300 watt, well I can tell you it’s not it’s probably a 100 watt. You have to look at the specs. It should say actual draw or usage that is the real wattage.

You are correct on what the idea behind scrog is, instead of vertical you force it in to a horizontal growth. This is done to maximize the light intake which you do not really have.

It is true a auto can finish in 70 to 80 days I find it rare, my current grow should finish up closer to 100 to 110 days.

The idea behind the lst approach to the pull the plant over to the side allowing light to reach the bottom of the stalk to encourage new bud growth on the lower section. Here was the light I started with a cheap blurple supposed to be 1000 watt, I use it now for seedlings

And here is my true grow light set up now a hlg 360 elite.

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I also run a veg tent I have two hlg 100’s in it.

Thank you Skorpion. I’ll work on my lighting setup. The HLG is a little out of my price range right now, but I can add some cfls for more light.

Still, I’m a little unclear on how to train these guys best. What should I do and when should I do it? Do I cut the main stem on a Sour D Auto, or just try to bend it to grow horizontally? What is FIMing? (it I missed, I get, but what is it in practice?).

As always, very grateful for the advice.

Can you explain FIM-ing to a newby?

@Eyes_of_the_World I’m on my first grow so a newbie as well, but while attempting my first topping and did a fim instead. Two others got a correct topping. So in my uneducated way, here it is lol. When you top you are attempting to cut the top growth of the main stem. This causes two to grow and replace what would have only been one top cola and now it will grow to be two. When you fim you don’t cut low enough and essentially cut into the growth instead of removing it. This causes it to grow in a variety of ways. Some have said they got multiple stems out of a fim. I believe the fim is more random and therefore topping is more reliable. Both temporarily stunt the growth and cause the plant to bush out a bit. People say topping an auto is bad because they are on their own timer and will flower when ready , so if you top you lose some veg time in theory. Some have success with it. If you aren’t convinced by the time you want to try it, maybe top one and see how it reacts. Then you can see without jeopardizing all your plants.


Go on you tube and type how to Fim a cannabis plant by Lex Blazer. it’s not hard once you see how it’s done. watch the video it is about 3 minutes long.


Problem with topping, fimming, or trying to scrog an auto is that you really don’t know when its going to start flowering. And the stress of any of them could send the plant into flower. So if you top or fim without adequate time to regrow you just lost your main cola. Same for the screen really. You probably won’t stress it into flowering, but no guarantee you will have time to train plant to the screen.

All of those methods better suited for photo plants. You’re hydro may help, but hard to say.

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Thank you all!

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I grow autos and if your in hydro or soil less mediums I suggest a FIM followed by some LST if you have time.

A FIM will produce 4 tops rather than one and give a more even canopy, it also does stress it but not as much as a topping that only gives 2 top colas. It also makes the plant produce growth hormone and you’ll see a bunch of growth after a little bit of a pause right post FIM’ing.
Another thing is it helps control the height of the plant, some can grow really big and even with a FIM it can be a struggle to not out grow your tent (unless your in soil which I don’t recommend using as an indoor cannabis medium)

FIM at the 4th node or right prior to pre flower, i prefer 4th node and the other local auto expert @Not2SureYet prefers right prior to pre flower /stretch.

I don’t think a scog on autos is worth it personally like @dbrn32 said, you need a longer veg time in my experience.

Oh and your gonna need a way better light, you get what you pay for when trying to imitate the Sun


[quote=“Nicky, post:14, topic:48840”]
I don’t think a scog on autos is worth it personally
[/quote] :open_mouth: LOL

Unless you are in coco where the veg time is longer maybe. :grin:
I scrog every body :grin: If it grows. it gets a screen :slightly_smiling_face: I have only done 2 fim’s correct my self. It seems harder than it looks to get just the right spot for me. I do top every one though :grin:

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I have a clue SD Auto’s growing now and did not top or fim them due to the voices of many saying not to. I am LST the one now and seems to be working well for me and the plant.

I am hoping for the best but planning on less yield than hoped for So I won’t be disappointed. :laughing:


Brian tag me on your next plant that is growing its 4th node… I’m making you successfully fim a plant! You need to do it!

I agree a tall auto in a autopot with coco can scrog

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@Nicky, will do. That will be real soon.

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@Nicky please tag me on the FIM.ming lesson. I’ve tried 3x and ended up either with no split and just cut leaves, or a true top split w 2 tops. IDK what I’m doing wrong. I have an auto SD ready right now. Was gonna just let it grow naturally, but if I can FIM and SCROG, that would be awesome.


Hey thanks for the tag and no problem.


Here is a video I made, I need to make another one with a closer video.

The first image is the most important.
if you push all 4 leafs up and bunch them together, notice where the stems brsnch into leaf.
You want to make sure that all 4 are left with 20% leaf structure if you cut it to short and there is no leaf structure then you won’t get a full fim with 4 colas.