Transition or not?

Yes definitely extend. I’m currently growing Pineapple Express and I didn’t extend before transition when I topped and I’ve stunted the plant about 40+ days.

I’m only now slowly reaching the second fan and it’s just over 110 days…

So yea. Extend.


Here is how i would determine if u should extend your vegetation to avoid stretch issues .

  1. Forget if its indica or sativa - your going from seed and pretty much everything u buy is a Poly-Hybrid
  2. Anticipate a 2x stretch for most cultivars except for Haze lineages in which case it would be 3x .
  3. U also want a 18-24 inch space between your lights and the top of the buds to avoid your buds cooking on the top.
  4. If u are unsure, lean towards the shorter vegetation period versus extending it out and your buds will touching the lights.

Wow 18-24” from the Grobo light? I honestly thought we could get much closer (within 6-8”) as the light is quite weak.

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Same thought here @SWSVIC, 6-8" seems to be the sweet spot in the grobo. Any closer and we really need to watch for burns. My tent light gets quite a bit warmer than the grobo light does.

I’ll be transitioning closer to the 1st fan rather than 2nd fan going forward, flipping “early” as opposed to later; haven’t had much luck waiting longer than that – they always hit the roof.


Fear I waited to long to transition on my current grow. Definitely implementing some veg/transition super cropping within the next couple of days and possibly putting in a second ScrOG 10-12 inches from the light to keep her trained under until week 2 or 3 of flower.


The further u get to the lights, the harder it is for the light to reach the bottom canopy. Personally for me 6 inches is way to close. Ill be using a Par meter to test the light intensity for PPFD and ill update it in my grow. My seedling on my thread is already at 100 par and its super far away from the light at the moment. I always side with the shorter vegetation period vs extending if in doubt. I grew plants that hit the lights and oh boy was it a disappointment in the end product.

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Which Par Meter are you running?


Apogee is definitely the leader of the pack. What is optimal PAR and PPFD for indoor growing? Are you aware of any good articles or research that you might be able to post a link to?

Your going to fall into the rabbit hole even more man. lol. This guy is one of the most respected lighting experts in the world. Watch his other videos when u have time.


I’ve seen bleaching on tips of a bud or two that were within an inch of or touching the light for a few days but haven’t had any issues lower than that, it seems to only be when they actually get so close as to touch the light (cover).

The problem (that I’ve had) with that area is the heat output from the light (causing sweating) more than the light being too bright – that’s what leaving some 6-8" helps with, in addition to less hands-on management required to keep it from hitting roof.

The plastic cover beneath the light seems to be designed to help to dampen the bright spots and spread the light around.

From what I understand the grobo lighting power/spectrum is well tuned (and dynamically adjustable by recipe/etc), with that tuning including the gloss/color of the paint on the walls.

Some higher-end android phones cameras/sensors can already come very close on par/ppfd approximations (there’s an app for that, usually just have to add 15-20% to get actual values); and the grobo seems pretty well tuned already based on typical node spacing/stretching seen in others’ and my grows.

I’d rather be measuring with something like this throughout a grow:


Killer deal under $7k! :stuck_out_tongue_winking_eye:

Here’s some prior discourse on this as well:


haha yeah, I meant “something like” – there are some for < $1000 that’s just the awesome one that will give you N samples per sec granularity etc

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Thank you, watched the first 15 mins. Really solid information, will finish tomorrow.

That’s a fiery link! Lots of great intel on lighting and Grobo policy.

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@vegetato Thats pretty expensive? Probably out of the range for most home growers. I also dont believe the grobo Led lighting produces UV and infrared? If there were , there should be multiple warning regarding clothing and eye protection? I recommend a 18-22 inch clearance for most people to avoid the light bleaching specifically and yes avoiding the heat production. Airflow seems to be effected as well with where the 2 fans are place if they are that close IMO. PPFD that is over 1000 is wasted since your plants can not photosynthesis without CO2 supplementation. I am not sure how the Grobo can tune their light according to the Cultivar since each seed is independent of one another with major variations. I am in the camp that recipes are a joke. lol. It cause the grower to doubt or speed up the vegetative process or discontinue the flowering phase without actually observing the plant specifically. They can change the intensity but to produce more blue or red light in the visible spectrum is unheard from my research beside actually physically adding diodes that contain more blue or red light. I would disagree with the Grobo being well tuned as the vegetative phase seems to produce very tight internodal spacing (too much blue light) while the flowering phase produces way to much stretch (not enough far Red light) and effecting bud development. Far-red: The Forgotten Photons - YouTube. A really good video on the effects of Red light specifically in the 660 range.

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Not sure about UV or infrared but it does have independent control over several parts of spectrum. I got to replace one of my lights and peeked at it, there’s quite a few diodes and a handful of them were “interesting” to say the least. I saw some that appeared to be far red but really not sure about the UV/IR.

When it starts up you can see it cycle between the colors, so they can be controlled independently. When I said dynamic I meant in intensity, though by turning certain ones on/off (or using the “interesting” ones) I think that you might be surprised.

With respect to stretching/etc I’ve seen both so far (great and stretches) so I do believe genetics and environment play a role so that some factors can’t simply be discounted or attributed to the box design alone.

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Chris the guy who works for Grobo, his account is suspended but he posted this in that thread to Chris barfield.
" answer your question you want 400~800 PPFD seen at the top of your plant for the seedling stage, 800~1000 PPFD for veg, and about 1000 PPFD for flower. This is a rule of thumb and quality of light affects these values. PPFD is a flat range from 400nm~700nm. This means you could theoretically have a blue light giving you 1000 PPFD, but that wouldn’t be good for your plant at all"

800 PPFD for seedling and 800 to 1000 for PPFD?? I would love to know where he got those numbers. Base from experience and other growers… That is extremely high IMO


Early veg phase according to the recipe - roughly 100 par which for seedlings I do agree with.