I need help, why so much stretch?

@dbrn32 if this next part sounds pre-typed, it is lol. I started putting my thoughts together yesterday and here is what my collection of brain cells produced:

"Let me give the long winded version for my opener, and I’ll trim down any future answers lol. I’m looking for a new light for my 4x4 grow tent. I’m currently working with a Viparspectra 700w (only pull 326w from the wall). The back story on this light is at time of purchase in 2017, the website claimed it would work with a 4x4 but they have since slashed that number and updated their stat page. (I only have a few screenshots to back my claim but it makes no difference at this point) To make up some difference with the VS700W , I recently bought a light mover. Together these are not doing it. I’m ready to put down some money and I’d rather built it myself.

Thus far, I made it to post 1200 of your 5,000 post thread, watched LED Gardeners build videos, and watched many of Growmau5’s videos and most of the 2.5 hour video he posted and while I have absorbed a ton, I just feel overwhelmed. I understand many of the numbers separately, PAR, temperature color, most of the concepts behind the driver its milliamps and such but I don’t know how to formulate my own build. So I’m hoping you can help.

Here are my goals:
-Cover a 4x4 tent from veg to flower: 3500k? CRI 90?
-Open to COB, strips or Quantum boards…the more I catch up on the forum posts, the more I see QBs
-Preferably a single fixture with a single driver
-Dimmable would be nice. I’m capable of soldering resistor.
-I’ll spend more on efficiency but I need low heat as it will be in a tent. (I have an exhaust fan and small desk fan in the tent)
-Not counting petty items: cable, tape, angle iron, wagos…I think I’m willing to put out about $550-ish on the light, heatsinks, driver.

I looked at a few HLG kits and I think I really like 320Watt XW Quantum Board LED Kit v2. This says it’s for 3.5x3.5’ max flower but I have a light mover. Could I use this in my 4x4?
Then I went and looked at the HLG 320 Watt XL Quantum Board LED Kit V2…and I thought…more boards, more diodes, more expensive, must be better coverage. Nope. The description compared to the previous light suggests using two. Now I’m confused.
I looked at the HLG-550 Quantum Board LED , too expensive…but can’t I build my own for cheaper? @MAXHeadRoom built a really good replica that I just found moments ago. If that would work in a 4x4, I’d like that. As long as I have the right boards and driver(s), I can get angled aluminum and make a frame

…before I get all gushy about QBs, is this the route to go?

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Any chance you have light leak too? 24 days after flip you should have a little more development than that, looks like all preflowers.


The vivosun tent is in great shape, and the room it’s in is already dark enough for a vampire during the day. When it setup/tested, I originally sat in it with a 500w worklamp on the outside and I was dark as night. I would actually recommend it!

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@EclecticJack Is it an indica? Most pure indicas tend to to do that. At what height did you start to flower? Anytime I flower in a tent I start at around 12 inches. You never know how much they will stretch. I have an OG Kush strain that needs at least 3 feet to stretch during flower so I can’t keep it in a tent.

Did you leave them in that DWC tub the entire time? Or transplant then force flowering? That would have given them a ton of room to stretch.

Happy Growing!

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Hmm, what about something you maybe have introduced into the tent? Or has anything changed with maybe your intake or exhaust ports? I’m not really questioning the quality of components, just that those plants should’ve been plenty mature to flower and 24 days in you should have clearly defined bud sites. Its worth taking a look at again just in case something has changed.

Don’t worry about explaining current situation, we’ve all been there.

You can absolutely save money on a build, and I would be more than happy to help you out. I have no preference on what you use but you will have to kind of prioritize what you want in order to see which direction is best for you. For instance, 3500k 90cri is a great spectrum to use. Unfortunately nothing currently available from hlg in that. Phillips has a strip, bridgelux vesta strips are close, or you can get just about any cob you want in that. However, all of those will be more sourcing and a little more labor intensive builds than something from hlg. You’ll also spend a little a little more getting something like a cob to run near qb efficiency levels. They’re all gonna grow good weed, just a matter of what is most important to you, what is next most important factor and so on.


It’s Barney’s LSD. Actually, I have a stat sheet for you…

They are fabric pots using Dyna-Gro nutrients
That plant is from seed and this it’s original pot, no transplant. When I flipped, there were two open squares around the perimeter, and the plants were about 4-ish inches above. I still tucked the next day or two after flip. I was keeping a journal on them here …

@monkman What are your day time and night time temps? I read an article in High Times years ago. It stated that if there was a huge difference in temperature causes a plant to stretch also. I remember it said it’s important to keep the temps consistent. Any significant difference will cause stretching and the internodes to be further apart. In other words, try to keep the temperature about the same during the day and night time. This will keep internodal spacing tight and minimize stretching.


daytime temp is @77 unless i let the sun shine on it like yesterday and then it is 84, don’t know what it is at night when light is off as i haven’t checked it yet. the ambient temp upstairs is 70 at night though so it should be somewhere right around there. i don’t think i have “excessive stretch”, it is just me not knowing what regular stretch is. i have one that is about 2 and half inches tall and 4 that are around 3 and half and that is probably just regular now that i’ve looked at others pictures on here.

I think the two biggest factors here are light intensity and proximity of plants. They don’t like to share the same place, so start touching each other want to grow vertical. This becomes magnified in situations where light intensity won’t offset any. And can be a pita even when the light intensity is good.


I completely agree that something should have budded by now…even if they were terrible and fluffy. That’s why I have literally thrown my hands up the last couple of days. The nodes have shrunk down, they have the look of where I would expect them to be about 7 days after flip.

The only changes from my previous grows are

  • No environmental changes (just technique changes listed below). I literally wrapped my last grow, cleaned the walls, carbon filter cover, and began my seeds. HOWEVER I do feel like the light is weaker but I don’t have any hard numbers to support that.
  • single plant, 5 gallon…usually I do two in three gallon
  • vegged about 10 days longer than any other grow before flipping. That was planned because I had more space with one plant.
  • I used molasses earlier this grow. 1tbs per gal @one feeding per week
  • I was using too much Cal-mag additive around week 4-5 during veg (vegged 8 weeks) but corrected that
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There’s only one plant. (Technically, there is a test runt to the left but it’s insignificant). I’ve had multiple plants that turned out fine. My last grow ended in November I had an auto growing next to a photo. Gave me about 8oz. Grow before that were two photos, only gave me about 7oz. Not only that I know these numbers should be better.

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Didn’t realize that sorry, that’s bad for 1 plant.

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@dbrn32 I know I’m going to be thinking over my head, but do you think I could build a light based around 4 of these boards…

With one driver based upon this build by @MAXHeadRoom

Which is based upon the HLG 550 I believe

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Now you see my pain. I planned for a big plant, I got a big plant, and now this big plant won’t flower.

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Yup, that kinda sucks. I think at this point i would probably try putting her in extended dark period and then back to 12/12. See if you can’t maybe give her a little boot in the ass.

I would also maybe take a look at sweep on your mover. Condense it a little so that bigger part of plant is constantly under full intensity. If edges are gonna be a little weak let them.

Ya 4 boards would be similar to hlg-550. I like going with two hlg-240h-c2100 drivers there. A dimming if you want built in dimming for each individual driver, or b dimming if you want to wire in potentiometer and control them individually or together.

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@dbrn32 The guy in that video used a HLG-480H-C2100B to run four.

Just because I’m a total lighting rookie, is there a benefit to using two drivers over a single or is it a necessity? (he also used 288s as opposed to my 324 idea…so I might have answered my own question)

  • Is there a lesser heat benefit?
  • can I wire the two drivers to a single power cord or would this just be like ‘two light kits on one rack with two power cables’?
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The “new” 324 is also 54v board just like the 288, so same drivers pretty much in play for either of them.

You can certainly use hlg-480, it’s about double the potential energy than hlg-240. In my opinion there are 2 reasons you would go with two driver setup over the single driver setup. The first, is potential to still have half of light in case of driver failure. They don’t prematurely flail a lot, and have 7 year warranty. But if and when it happens, half of your light should still be running until you get replacement.

The other, and perhaps biggest reason, is that two drivers will operate at half of the voltage. You don’t want to get into either of them, but in the event that happens I’d rather it be 120v than 230v.


Worth noting, more people die from 120 VAC electrocution than all other voltages combined. This is due to two reasons, first - everyone is potentially exposed to 120 VAC and second - most people think that 120 VAC is mostly harmless/safe and don’t exercise proper care when working around it.

By the way, DC is usually more damaging to tissue (at the same voltage) than AC.


Absolutely, good points to add. I ain’t trying to tangle with either haha.

  • I’m going to start a dark period tonight and not let the lights go back on until Saturday morning. that will be 60 hours of darkness.
  • I’ll tighten up the mover spread.

@dbrn32 So if you had 4 x QB324s with 2 x HLG 240s hanging over your plants in a 4x4 would you be happy?
Beyond exhaust and a small circulation fan would you be worried about heat?
It may not save this grow, but do you think this light will reduce my stretching issues and produce better buds for future grows?
What is the boiling temperature of vibranium?

Just kidding, but I’m sure it feels like 20 questions.

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