Led Distance From Seedlings

[Bashar Assad]

I have a bit of a question and iv been scouring Google all night looking for an answer but I just haven't found the info I want.

Here's what my germination area looks like right now. I have a closet set aside in my grow room for germination and seedlings, it's 2'x3'x6' has a sliding door that accommodates up to 3' of open space, and all four walls are covered in mylar up to 5'. There's a 12" oscillating fan on top of a five gallon bucket to circulate air. The seeds are germinated and then grown in a 12"x20"x18" Tupperware with two holes drilled in the side and one on the lid (small holes) to regulate air flow. There's a shallow dish of water in it and the seeds are kept in rock wool cubes set in ice trays with holes drilled in the bottom for drainage. For lighting I have a 60w 450nm/6.5k white led (3w x 20) on a pully.

Here's my question, what distance should I start my led off above my seedlings. I can see them just about to poke thru the top of the rock wool and I've been testing different heights of the led, fan speeds, and recording temp of another dome with each change in variable. Right now I have it up 30" from the floor (so 12" from the humidity dome and 28" from the new seedlings ) and I get a stable temp of 79*F under the led in my other dome. Is this a good distance to put the light at or should I get it closer? I just don't want to have put so much work into my tent set up (I'm making a post about it in another sub forum if you wanna check it out, I'm gonna call it "first timer set up, how's it look?" ) and then get light stretched or burnt plants! I know it's prolly not as easy as saying it should be x amount of inches above, but any idea of if I'm close to being at a good height is appreciated!

Thanks!

 

[Seamaiden]

I could really use a picture to see. :)

 

[Bashar Assad]

Okie Dokie gimme a couple minutes and I'll post up a pic. The germination and seedling phase of growing is the part of the plants life that I'm having a little trouble understanding. It seems everything I read is saying something different, so I thought I'd inquire.

The led is about 30" away from the floor and I'm in the middle of fixing up the mylar in there but I ran outta duct tape so it's like not gonna be pulled taught till later tonight.

 

[Seamaiden]

Ok, first, my opinion/experience, it's better to start off your cannabis seedlings like veggies in terms of whether or not to dome (I don't). As for getting them to germinate, I like doing that on paper towels before moving to soil, that way I know which ones are viable and which aren't and I don't waste my space and energy on those duds. But that's just me and how I like to do it, others do differently and do just fine doing it their way, too.

Now, I've never used LEDs for growing, but I would approach them like I would any other high-powered light, and this is based on my experience growing corals and Tridacnid clams--start high, then lower down as they become acclimated or demonstrate that they need more light. Depending on the intensity of the light, this may be as high as 5'-6' (I'm talking 1,000W MH type lights, stuff that puts out UV radiation and really does burn). Lowering can take as little as a couple of days, depending on how the plants respond, or as long as two weeks.

That is how I would approach the LEDs here. Have the seedlings popped, and if so, are they leaning towards the LEDs or any other light? If they're leaning (aka phototropism) then I'd begin lowering to a goal height I'm guessing of about 12"-18".

You have the fan oscillating, yes? Let it blow across the seedlings, they'll like that.

 

[Bashar Assad]

Okay I have one more question that's really confusing me as everything I read says the opposite of the last thing I read about this and even the growing bible confuses me. I think it's mainly because of the terminology and because I'm not to used to it.

Okay I just checked my dome and both my rock wool cubes have little sprouts poking put of them, just a few millimeters high. Okay so they're germinated now and are seedlings correct? So what do I keep the domes humidity at, and when or do I take the top off? Cuz like I've read that once they come up to take the dome off and I've also read to keep the humidity at 70%-90%ish. That confuses me because if I take the lid off the humidity is gonna be pretty damn hard for me to keep that high.

I got the light thing down now, but I really don't get where to go once they sprout (which is now heh these are my seeds that im learning to grow with, once i get everything down, i have better seeds to use) it seems everything I read says either lower humidity and no dome (treating them like they're vegging) or high humidity and keep the dome over them.

Yea I thought I had this part down but I was going over the seedling phase last night and ended up just confusing myself with all the stuff I read. I think I'll take a while to find some really accurate info on this for now.

 

[Seamaiden]

You can keep the lid on partially, but you need to understand that if you do keep it on and don't harden them off properly to the new humidity conditions once they outgrow it, there may be losses. Me? They all go outside.

You're getting to experience opinions. At a certain point, you've gotta just do it for yourself and see what works best for you.

 

[gardnguyahoy]

As far as i know, led's are like lasers. It doesnt matter the distance indoors cause you cannot put it a far enough distance to dissapate the light, as far as i know. Anyone is welcome to agree or correct me.

But, what ive read and learned is that theyre nothing like hid or cfl as far as short indoor distances changing light intensity to the actual plant. If you put a plant under a 100w led. Wether its two inches or ten feet those plants will receive the full 100 watts, given that the led's are pointed straight at the correct target.

Again, just amongst things ive read and learned, not stated as personal exp. Or fact at all. Keep growin, and listen to advice given by Sea. She knows whats up

 

[sixstring]

As far as i know, led's are like lasers. It doesnt matter the distance indoors cause you cannot put it a far enough distance to dissapate the light, as far as i know. Anyone is welcome to agree or correct me.

But, what ive read and learned is that theyre nothing like hid or cfl as far as short indoor distances changing light intensity to the actual plant. If you put a plant under a 100w led. Wether its two inches or ten feet those plants will receive the full 100 watts, given that the led's are pointed straight at the correct target.

Again, just amongst things ive read and learned, not stated as personal exp. Or fact at all. Keep growin, and listen to advice given by Sea. She knows whats up

if this was true led would be far and away the best light ever lol.but light is light and the stronger it is the more penatration you get into the plants,developing lower bud sites.this is why hid perform better than most led.plus i notice with any led company they seem to be able to make up any watt number they want.hardly ever does a 100w led panel actually pull 100w from the wall or even put out 100w at the bulb/diode.its like cfls except at least with cfl/floros they say actual watts and "replaces xxx watt incadesant bulbs on the package.with led they just make up numbers it seems.
but no man,if you hang a mars ufo say 190w on a 10 foot ceiling and put a seedling under it it will stretch like a mofo to try and get at that light source.but if you hang it 10 inches above the plant it will grow nice and bushy.

 

[gardnguyahoy]

See ^ there's your answer. Thanks for clearing this led mess up @sixstring

 

[Bashar Assad]

Alrighty! Thanks for all the replies guys :). So I decided to scrap using my 60w led in favor of a few cfl's and florescent tubes. I just couldn't get the led to get to the right height without the heat going up too much or some other problem.

So I bought three 40w 150 watt equivalent, 4100k, 2600 lumen cfl's and two florescent tubes (full spectrum, 900 lumens, 2' long) with ballast and reflector. Basically the tubes will be set up close as possible to the seedlings (2"-3" above heat permitting) and the 40w cfl's will be hung partially to the sides of the tubes as the reflector/ballast will block thier light if they're right above. The cfl's are hung with clips and are powered by light sockets attached to 4 foot cords.

I get the tubes tomorrow in the mail, so for now I have the cfl's hung 12" directly above the seedling. Any closer and it seems to get to hot at seedling level. I'd rather not burn my plants to death and have em stretch a bit heh.

So I think I got this right for how my seedling should be set up. I have it like this...

Seedling in a tray, under cfl's as mentioned above. There's a 12" oscillating fan blowing on the cfl's to cool the air they heat up. I put a 4" fan on a hanger bar in the closet to blow diagonally, which dissapates the air around the cfl's as well as circulates the air around the seedling. I bought a humidifier today to crank up the humidity as it was at the low 40's early today and now hits a high of 70% RH, which I believe is good. The temp. With the fans going, room ac on and lights on is 77*F at seedling level and at lights off its a bit lower because the lights are off.

I'll post some pics of my set up.

So am I on the right track?

 

[Wisher619]

lower your cfl's down to about 2-4" from that seedling....when I use my Floro's when I germ or clone I literally have the light 2" from the seedlings or clone......not just Cannabis...all my veg....I figure it is better as intense as possible without burning them as soon as they break ground....preparing them for the sun or HID light...makes them
stronger as well as stocky and tighter internodes

 

[Bashar Assad]

I found that the lowest I can put them is around 8"-12" as any closer Jacks the heat up at the seedlings level like crazy. Even with ac and fans on too. I'm going to put the tubes about 3" above them tho so that'll be good right? I was thinking of putting my cfl's on the side of the seedling tray as I can't fit them above. Is that okay?

 

[gardnguyahoy]

Looks like a fun setup. Id personally seal the area off and find a way to run the a\c directly in and vent the heat from the bulbs directly out.

A better circulation system will help keep temps down. And essentially get those ligghts closer for you. Those look like self ballast cfls, hot hot hot. Good luck. That seed needs some tlc my dude

 

[Seamaiden]

Brother, at this point, why not just buy some cheap shop lights and go with a full bank of those? Hell, I've been able to grow hermatypic (reef building) corals and Tridacnid (giant) clams using *nothing* but shop lights stuffed together, mixing the colors myself.

You'll get better spread of the light, you won't have to fuck around with all those clips and exposed bulbs, and it's just a neater installation while still getting plenty of light to the seedlings.

Just a suggestion.

 

[gardnguyahoy]

Shop lights?

Brother, at this point, why not just buy some cheap shop lights and go with a full bank of those? Hell, I've been able to grow hermatypic (reef building) corals and Tridacnid (giant) clams using *nothing* but shop lights stuffed together, mixing the colors myself.

You'll get better spread of the light, you won't have to fuck around with all those clips and exposed bulbs, and it's just a neater installation while still getting plenty of light to the seedlings.

Just a suggestion.

 

[Wisher619]

Shop Lights

 

[Bashar Assad]

I should be getting my florescent tubes at anytime now today from amazon. Seeing how those run a lot cooler I'm going to put them right 3" above the seedling and use the other cfl's as supplement light.

Oh speak of the devil they just here! Alrighty let's do this!

 

[Wisher619]

you won't really need supplemental light once you have the Floro's....you just sit it on top of the seedlings and call it a day...I use them for my seedlings/clone/mothers/veg pre outdoor...

 

[Bashar Assad]

Oh really well alrighty Ren I'll turn em off seeing as they're just heating up the closet. I'll save them for the tent!

 

[gardnguyahoy]

Oh really well alrighty Ren I'll turn em off seeing as they're just heating up the closet. I'll save them for the tent!

Lol... The scooby doo accent?