Autoflower questions on trimming and temp

This is my second time growing autos of different kinds and my wife likes to trim a lot and I say let ‘em grow with out trimming so hard. She did not trim first 8 weeks and then she could not stand it and trimmed them. Now leaves are turning yellowish. Also it’s been cold at night but in green house so they can got hot on sunny days.

All advice welcomed.

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Welcome @Low-kal to the community! So, what was your question? Autos are 8 weeks old in a greenhouse. Ya, gets cold at night here (Vancouver area) and mine are just outside, no greenhouse! Ok, have 3 budding in a tent too.
Upload a pic or 2 of them if you can. Wait until pics are loaded and “processed” before you hit Reply again. And pics must be under 4mb size.

Good advice so far. Autoflower plants can be thought of like a firecracker or old fashioned cartoon rocket… Once you water the seed and show it the light, it’s going to “go off” and do what it’s programmed in its dna to do.

Early in its short life it deploys leaves as solar panels to make the sugars it puts in the roots to make the flowers with. Once a leaf is yellowed and limp, and no longer using sunlight to store sugar in the ground, the leaf is done and can be removed. Any time you take a green leaf, you throw away your ability to turn sunlight into sugars. Once the leaf is no longer green, it’s not making any sugar and you can take it without stunting the plant. Any time you take a green leaf, ask yourself why. If you need to unblock choked airflow and avoid rot, ok, just understand what it costs. You’re throwing away the engine that makes the stuff the plant grows with. In forest management the term is “down and dead.” If it’s not dead, you can always think about reviving the engine that makes the sugars that makes the good stuff. But if it ain’t green, it’s no longer doing the spelling test word we all hated in grade four. The leaf lives to provide shade and turn sunlight into sugar. If it isn’t doing either, it’s gonna rot, and where there is rot there is potential for mold. But once gone, it’s gone. It’s a choice to lose a potential generator and sun shade or risk rot and blocking sunlight from the living parts.
That’s why we use the little fans waving the air around. No dark corners. Aired out and no mold, thanks. But if it’s green, it’s a sugar making machine. Try not to lose it if you can help it. Life is very short for autoflowers. Don’t waste time and potential by throwing too many leaves in the trash. You can’t get that back, and it won’t make nice, fat buds if it hasn’t got the sugars made in the leaves…


Defoliation and pruning at the correct times are very important for the healthy growth of the plant.

From my limited experience with autos, they are more sensitive to defoliation or hst.

Phenos seem to take pretty much whatever I give them. I prefer to train primarily with hst but that does not work so well with autos as I’ve found out:

If the plant has begun flower I’d treat it just like a photo.

I like to Hst all the way up to a week before flower with as little defoliation as possible on photos. On Autos I am no longer doing any hst and only plucking leaves blocking flower sites or to gain air flow through the can. As far as how much defoliation depends on the plant and it’s spacing. Squat plants will need a little more work.

After week 3 of flower do your major pruning and defoliation. After this defoliation you are good the rest the way as they won’t grow in new leaves. I try to leave a good mix of new and older leaves that are healthy. Just make sure to leave a good amount. I like to leave a couple mature ones on each branch and all the newer ones that aren’t blocking. Don’t do any trimming after flower starts until after the stretch.

Prior to this point, I would personally go light on autos. I would only cut any bottom leaves not getting light as they are just sucking energy from the plant and any damaged leaves the plant has to waste energy on.


thnx you answered a couple of my question’s ! I was wondering about topping , LST or pruning my auto’s.


I’m doing autos for over a year now, and I’m convinced they need as many healthy leaves as possible because the more green leaf surface, the more photosynthesis, which means more sugars being stored in the roots.
This one s why transplant shock wrecks yield. The root hairs get damaged, effectively losing the keys to the safe deposit boxes full of sugars the plant uses to flower. Yield beyond just fluffy little larf is directly proportional to the amount of sunlight the plant could convert to sugar and later retrieve from storage in the roots. Look at the videos of the big l, plate of spaghetti looking roots. That’s the storage network. Lotta leaves and a healthy root system.

So nope, unless a leaf is beyond healing, shriveled and limp or dead dry, I ask myself if I can help it get air and light and not dark and not on the ground. That’s protecting my sugar factories. Then as the plant starts to bud, are fan leaves blocking significant lower buds? If so, judgements are made as to which leaves can go to get light in, but not so many I starve it. It’s a balance.


I always FIM my plants they’re autos always once end of week 2 then once again end of week 3 then by 4th week they are healed and go into flower perfect timing is required. I keep it all documented on my calendar when plants sprouted etc. Always get big bushes many main colas

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Hi this is my 1st grow w/ auto’s 3 of the girls are flowering already ( the’re at 3 weeks n 3 day’s from when they were planted in their forever 5 gal. fabric pot’s) I was wondering about LST n topping ? I’m too late w/ 3 of them to top but 4 haven’t started to bud /flower . I’m also having some issues w/ yellowing on the bottom leaves on 3 of the girl’s , as if deficient in something or too much of something or too hot soil , I’m using COM super soil (coast of maine )

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Fim them you won’t be sorry fimming is done by cutting new growth at top of plant 70 to 80% of new growth gets cut with clean scissors you get a big bush with a bunch of colas

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The advise here is excellent. I’ll tell you about my LST. I’m on my 3rd grow. My 2nd was 12, yes 12, plants. I decided to LST 1/2 and let the other half do their thing. I’m getting bigger buds on my LSTed plants, which I also defoliated fairly well. I’m getting 1.5 to 2.5 oz per plant on the three I’ve harvested so far.

The plants I didn’t defoliate are bushes – they freak me out.


The more I read and practice, I’m convinced the limiting factors with autos have to do with their more pre-programmed life cycle. Unlike photos, autos are unforgiving stresses like FIM, or other HST techniques. Even transplant stress can submarine yield by creating a runt of an already “rushed” auto.

I’ve tried topping vs LST tying down, and in a side by side battle of sisters, the LST plant outweighed her sis by about twenty percent. That was doing almost nothing else.

As above, I defoliate with a mind toward the permanence of the loss of a sugar factory. I’d rather add a fan than take leaves.

So my LST “without a net” technique has evolved to simply tying down the young plant, exposing what will be the lower bud sites to the light, and to a bigger share of the stuff the plant sends to the top. It’s the same hormonal signal as when topping, enhancing secondary colas without losing the primary top.

It’s accomplished using pipe cleaners to tie the plant down to the rim of the fabric pot. Poke a hole and create a tie down, repeat as needed for a couple of weeks around the week three to week five window. Tie the top down, and adjust as needed, adding a second or third tie down as the plant grows. By week five the stem is roughly a horizontal “7”, shape, as if it was going to ring the pot.

At the first sign of preflower, around five weeks since sprouting, stop messing with it. No additional ties, and let it chase the light. Leave the existing ties loose. Within days the stem will take on the shape of a lounge chair like at the beach, fighting the horizontal curve,working toward the light. I leave the restraints very loose, looping the pipe cleaner over rather than twisted, so the growing plant can fight back. These are 35 days above ground, and officially done training. I think I may have taken a total of ten leaves for various reasons for three plants in five weeks.

They’ll have decent main colas and a compliment of secondaries.

Everything we do that stresses the plant costs. Factor the costs when trying to get benefits from stressing.

image image

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o.k. so I am digesting the advice on topping n LST .I need to figure out why my girls leaves are yellowing ,at first I thought it was due to energy going to the flowering / budding but it’s going up the plant’s & not just on the bottom also the new leaves that are coming out are looking like their whithering or drying out , leaves looking really skinny as if they just sprouted the leaf but they feel very dry & leaves aren’t widening out just looking like skinny canoe’s curling under .I know it’s hard to understand what I’m talking about w/out seeing it ,I’m trying to figure out how to load my pic’s from my phone .I did on another site I was on but I don’t seem to be able to figure out how to upload pic’s on this forum ( not sure why???) all my girls looked really healthy n robust now some of them are looking sickish ( the ones flowering ,not the one’s that haven’t started to flower yet ) please any advice will be appreciated .

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o.k. I think I figured it out ,ugh !! so here’s one of my girls the biggest one .this pic is about 3 day’s old ,I’'l post another post n w/ more pic’s now that I figured out how to do it .

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just a side note I cut off the yellow leaves that she had on it ( I was told that their not doing to do anything benificial for the plant leaving them on so off they came.but as you can see the new leaves are dry to the touch n r curling a bit now ,at first i thought I overwatered but my soil test thing said the soil was dry (all the time) so i watered a bit more the last 2 times i watered them. but could it be i need to add something ?? bone meal,etc. I’m using COM (coast of maine) soil n ammendments ( i’m using all COM product’s) temp is day 83 84 degrees night is 77degrees ,humidity is 43% rh water is 6.0 ph soil is 7.0 ph ,I set my lights at 75% now ( I did have it at 100% ) & about 18" above their canopy give or take an ich or 2 .plus i water in a circle n not on top of the plant’s.tip’s advice PLEASE !!!

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This is a Bubblegum Auto in 5th week of flower. This is the last one that I topped. The Blueberry and cream are about 5th week in veg and I haven’t even touched them yet.

As you can see… HST can work if you time it well. I have an OG Kush I chopped and fed to the worms as it freaked out when it went to flower. LST is the safe bet on autos.

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Every plant seems to be a little different. But ideally I would like to at least shave the bottom thirds and take a couple leaves prior to stretch. It just makes for a better shape and the increased lighting makes up for the couple leaves. Just try to get your moneys worth…Study the plant and see what’s gonna get you the most benefit. Not cutting leaves just to cut them.

So it is pretty similar to a photo prior to stretch (knock off the ugly stuff you don’t want growing) then let them go till end of week three and then you will have to clean the canopy and shave anything you missed on the lower thirds.

These plants are same age - one phenotype and one auto. So you can see the pre stretch trim is similar except for topping and the autos get a couple more branches off the side stems.

Strawberry/ OG Photo - Hard pruning (tops) plus shaving the stems and some defoliation. Once satisfied with the shape and spacing I top dress and send to flower about 5-7 days later.

Cream Auto - No hard pruning (no tops) but still cleaning the lowers of stuff I don’t want and shaping the plant. Personally I just don’t like LST other than massaging the stems in the direction I want them to go once in a while while doing some super cropping. This plant I chopped the 1st and 5th nodes to get the shape/ spacing I wanted and then shaved the stems. The only difference is I allowed for a couple side shoots off the stems I kept since I won’t have tops. Im not too worried about moving a some key leaves as I will have an abundance after stretch is done.

(is that a lot easier than tying her down for two months?). Seems much less stressful long term to me. LST for me is increased air movement building knuckles so I don’t have to trellis.

If your leaves feel dry and crispy may need to water down to the bottom. As far as leaf deficiencies… Make sure your AUTOs are getting enough cal/mag as they require more than photos and may not be enough in your soil. I supplement some form of cal/mag every other water.

COM is great soil… IMO similar to FFOF. Although its claimed to power your plant from seed to harvest that is not true. You would need at least a 15-20gal pot for that and still questionable to me. Make sure you start ammending by week 4-5 from seed.

Since you are growing organic I wouldn’t worry about ph. Using RO water I would definitely be adding addionaly micro nutes and using cal/mag every water.

As far as lighting, 18 inches is a good height in flower. Depending on your lights power you may need to get closer to 90% through week 6-7. Then I would back off 5% a week or raise the light an inch or two till they finish. Turn it up as high as possible… Put you hand right above the canopy… If uncomfortably warm, lower intensity or raise the lights. Or buy a par meter. Keep plenty of airflow between the canopy and the lights.

Yellowing on bottom leaves… Sounds like your girls ran out of nitrogen. But could also be cal/mag so make sure that box is checked also.

Frankly, you are almost to week 4 of flower. You soil PH to me seems like there is something your plants are not uptaking and it is staying in the soil and they depleted the things they like. So your soil is hot but its not. Personally, I would flush a couple gallons out the bottom, top dress a couple days later with full organic ammendments, and water them in with worm castings, kelp, and molasses. These will feed your plants immediately while also breaking down the ammendments.

Takes the guess work out of it so you are not chasing your tail one ingredient at a time and the ammendments should be ready for uptake right about week 5.

thank you, thank you, thank you! I have been stressing over this grow, I went thru 12 seeds & a bit of cash ugh ! b4 I did this grow (they were autos as well) they all died due to my lack of knowledge n either doing everything wrong or not doing something. So, I believe I’ve got part of my problem solved ,my soil meter tester always said they were dry+ (meaning very dry I’m guessing) I always watered 1st of all in a circle around each girl , but I didn’t water a lot I was afraid of overwatering & drowning the girls. I watered some more till my meter said either wet or almost wet ( I was always so afraid of too much H20 ) anyway, I noticed the leaves on some of them are softening & uncurling a bit so I think the watering issue is doing better. Now for the lights ( Mars hydro tsw 2000, 300 watt) I turned it down to 75% I did have it on 100% (I thought the leaves were curling cause of heat ) but,I put my hand like you said to do n it’s not hot at all , so I’ll probably turn it up again to 100% as for the CAL / MAG is that the same as FISH BONE MEAL? it says on COM’s feeding schedule to add it around 30 days in (from seed I assume ) to the top of the soil & mix in & then water. so as u can see I’m a newbie grower especially auto’s what is micro-nutes ? I’m getting better fan’s but for now I have 3 smallish one’s , 2 on top n 1 on the bottom (I’m not using CO2,not sure how to do it & do I need to do it?) as for the yellowing of the leaves it starts out on the bottom & goes up the plant eventually ( see attached pic’s) how do I know which one the girls are deficient in? cal-mag or nitrogen ? my soil ph is 7.0 my girls were all germinated n planted at the same time but a number of them had helmet head so that’s why I’m assuming their in diff. stages of growth. some are already in flower n some aren’t ( as you’ll see in the attached pic’s)as for the soil being hot but not , lol I thought 7.0 was good for the soil to be ? could you elaborate a bit ? Could you break it down specifically as to what mean’s " full organic amendments " I have COM fish bone meal & their worm casting’s mix but no kelp , also when n how should I use molasses? It’s a bit confusing as to how n when to add all these supplements ,I need specific instruction’s on it all ( I learn better by watching so since I can’t do that, specific directions work best for me) & that’s what I didn’t want to do is add one ingredient after another that’s when I get really confused.I Luv my girls n I Luv to work in the garden even if mine is indoors, heh, heh! but it’s getting a bit overwhelming when I’m not sure what I’m doing ( sometimes) & I don’t want to kill them or spend tons of money either .again thnx for all your advice & patience. BTW they are Kush XL & triple XL autos. Any advice on good auto’s you’ve grown? I like hybrids, Indica dominate or Sativa dom. don’t like full-blown sativa’s makes my heart race & sometimes dizzy too.again thnx !!!

forgot the pic’s ,lol

i thought i uploaded all the pics … but only 2 of my girls pic’s actually uploaded anyway these 2 are the furthest along in growth the other girl’s are smaller I actually topped 3 of the girl’s & i’m doing some LST on a few of them too .I’m going to see why all my pic’s didn’t upload on here.