Seedlings under heavy lighting test

My thoughts about are that in places like Columbia, Vietnam, Hawaii, Australia, Laos like yours, and especially at high altitudes, seedlings get huge amounts of light, and UVA/B from the very start.
I started out in the 70s and have been using 1000w HID since they very first came out. I used to use a 1000w Halide to start Seedings-Flowering, but when Hortilux came out with the 1000w HPS Superbulb in the 90s I switched. I use them from Seedling-Flowering.
I use a 1000w Hortilux HPS for every 4 x 4 area. I normally use 3 of them in a 12 x 4 area.

I also grow large plants as Im in an unfriendly state, and try to keep plant count somewhat low. I veg in 5 gallon buckets of Promix BX, and transplant/Flower them in 2o Gallons of Promix BX per plant. I can get 6 plants under the 3 lights, and then I can strategically locate another 5-6 plants in 5 gallon containers, though I have to elevate them to obtain a more even canopy, and not shade them to much.
I got 83oz like this last harvest using an old cut from 2010 of Barneys Farm G13 x Haze, before the company, IMHO went to shit. This stuff also stretches 3-5 times its size after putting them in 12/12. I myself like plants that stretch because it decreases veg time. I also dont top my plants, I bend them over. All the side branching turns into huge colas. My best single plant doing it like that in a 4 x 4 area is 23oz from the G13 x Haze, and 60 days veg. I also let them veg 1 week after transplanting from 5 gallons, to 20 gallons. Also If I leave them in a 5 gallon container, they will only stretch about 1.5-2 times their size, and produce at most 6 ounces, as where I can easily get 16 ounces from the same plant transplanted into 20 gallons soil with 45 days veg.

Ive never really used anything less than a 1000w HID from start to finish in 45 years, and have never had one problem. And if Im trying for the fastest growth, I also start them, and veg them under 24/7. Every 3 days I may turn the lights off for 6 hours just to rest the Ballast.

I dont know how many lux a 1000w Hortilux HPS but I know its alot at 20-24 inches. I have the light 20-24 inches from the top of the plants.

I have also started seedlings under a 1150w Gavita, at 36-40 inches with no problems. Only thing you have to worry about with either light is heat, and I can keep my temps from 78f-86f, and have found they have no problems with this temperature spread. I also do have a huge amount of fresh air flow, which I think is critical. The less air exchange, and higher temps will eventually cause problems. I also keep a breeze blowing on plants-seedlings-Flowering 24/7 to induce strong stems, and branches.

jimihendrix1 said:

My thoughts about are that in places like Columbia, Vietnam, Hawaii, Australia, Laos like yours, and especially at high altitudes, seedlings get huge amounts of light, and UVA/B from the very start.
I started out in the 70s and have been using 1000w HID since they very first came out. I used to use a 1000w Halide to start Seedings-Flowering, but when Hortilux came out wht the 1000w HPS Superbulb in the 90s I switched. I use them from Seedling-Flowering.
I use a 1000w Hortilus HPS for every 4 x 4 area. I normally use 3 of them in a 12 x 4 area.

Ive never really used anything less than a 1000w HID from start to finish in 45 years, and have never had one problem. And unless Im not tryong for the fastest growth, I also start them, and veg them under 24/7. Every 3 days I may turn the lights off for 6 hours just to rest the Ballast.

I dont know how many lux a 1000w Hortilux HPS but I know its alot. I also have the light 20-24 inches from the top of the plants.

I also start seedling under a 1150w Gavita, at 36-40 inches with no problems. Only thing you have to worry about with either light is heat, and I can keep my temps from 78f-86f, and have found they have no problems with this temperature spread. I also do have a huge amount of fresh air flow, which I think is critical. The less air exchange, and higher temps will eventually cause problems. Also also keep a breeze blowing on plants-seedlings 24/7 to induce strong stems, and branches.

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I was going to do 3-4 weeks under the lamp (moving to a 4 way splitter with 2x3000k and 2x6500k 11w bulbs after a week or two, sticking to the recommended 15k lux for early veg and increasing gradually week by week) and then move it into the tent for flip and see the difference, but It became apparent after 9 days that I'll have a stringy mess with next to no satellite growth after two or so weeks, and knowing my luck it'll be the only fem.

Sometimes I wonder how the "accepted literature" became so accepted if it's plain disingenuous. For example, numerous sites using the lux chart claimed that anything over 10k-15 lux for seedlings can cause burn and stunting, but shade under my verandah on a sunny day is 30k lux or more. I don't see how 1/3rd of the intensity provided by a shaded area would damage a seedling in any way.

I would have liked to do this properly with a real side by side over 4 weeks, but reg seeds, hiding growing and space limits made me bail.

Lux isn't the right metric to use available plant light so that approach is flawed from the beginning

Jimi I think you could save some bucks on electricity if you just use a less big lamp at a closer distance and start sprouts not in gigantic sized pots, to be able to keep them closer together

it's all about the ppfd and even a small lamp can give 400-600ppfd, though at some point that diminishes too strongly further down so with increased plant height it naturally calls for a lamp power upgrade

Kassiopeija said:

Lux isn't the right metric to use available plant light so that approach is flawed from the beginning

Jimi I think you could save some bucks on electricity if you just use a less big lamp at a closer distance and start sprouts not in gigantic sized pots, to be able to keep them closer together

it's all about the ppfd and even a small lamp can give 400-600ppfd, though at some point that diminishes too strongly further down so with increased plant height it naturally calls for a lamp power upgrade

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Lux can be converted to par with pretty decent accuracy anyway if your running calibrated to spectrum. The conversion is above from what I believe.

I used to live with someone that had a nice lux meter and when I rented the apogee a few months back, 35k lux at 4000k was equal to 565umol, and 60k lux read just under 1000umol/s, which comes extremely close to Migros formula.

7.5k lux at 4000k was something like 135umol/s.

If I had a par Meter I would have used it lol. This wasn't about ultimate accuracy with PAR measurements, more so about the 10-15 well known sites that use the lux charts for optimal lighting for germ and seedlings, which I think is straight bogus.

Thanks for posting your experiment. I think that solves a problem I had.

Kassiopeija said:

Lux isn't the right metric to use available plant light so that approach is flawed from the beginning

Jimi I think you could save some bucks on electricity if you just use a less big lamp at a closer distance and start sprouts not in gigantic sized pots, to be able to keep them closer together

it's all about the ppfd and even a small lamp can give 400-600ppfd, though at some point that diminishes too strongly further down so with increased plant height it naturally calls for a lamp power upgrade

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I start my seeds/clones in a 32oz Uline Deli container, then when they grow out of those theyre transplanted into a 5 gallon container for veg. I root clones by keeping them far enough away from the HPS as to not kill them. About 6 feet.

Offmymeds said:

Thanks for posting your experiment. I think that solves a problem I had.

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just wishing i left it a bit longer to get a better gauge of structure, but i had to bury it twice already in 9 days so i quit lol. watching a lot of feeds from large scale groweries and reputable breeders and they all used a max PAR of 450-500umol/s during veg and noticed their plants were very stretched compared to mine. Had me thinking there might be a benefit to that type of structure if the room is available so i am kinda wishing I held off and threw it in another tent to see if that is so. I've always ran 700-800umol/s (40-50k ish lux) from the get go all the way through as I usually run autos.

If they were all feminized photos, not regs I would have continued for sure but the thought of the leggy plant being the only fem ate me up.

guess the breeders do everything to scale plant structure down to increase plant count

It's more or less what was expected, but it still got me thinking about why I do what I do.

I bombard the plants with light and have tight node spacing, getting dense buds and minimal stretch in a 72" tent. I suppose I can get away with it considering my low humidity. I don't push hard or try to maximize everything, so it works for my sloppy ass.

Except this last grow with a sativa. Loose buds, massive stretch - first time I had the light at max height in the tent!

Like so much, the nuance of care originates in genetics. I still want some quality bar lighting - upgrade my 300W LED hood to something in the 400W range that's spread out over the whole 4x4.

It's a waste of electricity is all.

calvin.m16 said:

It's a waste of electricity is all.

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The light is already on. I have more than these seedlings in the tent.

Setting up a second tent for seedlings would actually increase my energy usage.

Another thing you didn't factor in is that light intensity doesn't just come from energy usage, it also comes with proximity. I can provide 35k lux with an 11w desk lamp 6" away.

This was about intensity, not power. I could dim my qb to 40w, drop it to 6" and it would be sitting around 90k lux.

The difference between the "recommended" intensity from pop and max veg intensity from pop is pretty big even over 11-12 days.

The one started at 7.5k lux and moved to 15k after a few days is stunted, lime green and has no viable satellite growth yet.

The ones started at 35k lux and moved to 45k after 3 days have considerable satellite growth, greener hue and are far healthier all round. The top and bottom pics are in 8" pots, the middle is in a 5" pot.


The stunted one has been under 45k lux for a few days now and hasn't really taken off, and if anything seems to be struggling with the light as the day goes on. It's starts out okay, but by 12 hours in its drooping and showing stress, by lights off it looks like shit lol.

I officially boycott all of these recommended lighting charts for early stages from here on.

Interesting though, two look like the BCN critical mother's, and one looks more sativa already from the Laos male. Pheno differences in a strain that hasn't been stabilised is going to be interesting.

Ended up tossing the one started under less intense light. Still had next to no branching and was a few nodes behind. That 9 days under "recommended" lighting sure stunted the hell out of it. Left with two vastly different phenos. One with more satellite growth than the other.

It has been 5-15c lately. Even during lights on its struggling to get to 20c in the tent with exhaust on minimum. Plants at 55k lux currently and will be flipped to flower in a few days after they recover from topping. Were at node 7, topped down to 5. Potting mix looks pretty hot as well. Some cheap $7 potting mix with slow release prills in it.

VincenzioVonHook said:

It has been 5-15c lately. Even during lights on its struggling to get to 20c in the tent with exhaust on minimum.

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Getting cool here too, under 10c sometimes. I had this crazy idea to remove the exhaust fan from the top of my veg tent so that that ducting now becomes the intake and the air flows directly onto the led driver and down. Then at the bottom, what used to be the intake duct is now the exhaust but it flows into one of the intakes for the flower tent.

Because it's so backwards and inefficient it should work great to up the heat in both tents.