Distance from light and Umols

[The Villan]

Hello after reading the thread from 2016 by @GSZZ I was hoping he might be able to answer a question for me.

I am using my Par + Ultra led light for the first time to raise my newly sprouted seedlings. I have positioned the light so that on 25% power the umols are 110 at the top of the seedlings.

The light is about 2 ft away from the seedlings. I would normally have my t5's much closer trying to avoid them stretching too much. Given where my ligt is 2ft away and the umols are 110 will this be sufficient to stop them stretching for the light or should I use the mesh settings and move the light lower and adjust the umols as necessary ?

 

[GSZZ]

Its not about how far away the fixture is to the plants, but the amount of light they're receiving. I like to just hang my lights as high as they'll go and adjust the PPFD with the wattage accordingly. I actually think plants stretch more when you continually keep raising the fixture.

 

The only reason we had to put T5 fixtures so close to our plants/leave them on for 24/0 in the first place was to get the correct amount of light on our plants to stop stretching/noodly growth (even if we didnt know thats what we were doing, neccesarily) due to the T5s being so inefficient.

 

110 ppfd would be a bit low for me tbh, I start at 250ppfd.

 

 

[MindSoup]

9 minutes ago, GSZZ said:

but the amount of light they're receiving

 

And the spectrum, below 20% blue will cause wider internodal spacing and having a lot of far red/ir can do the same. Think t5s and halides and how they're better for veg than HPS. 

 

@The Villan 110ppfd in incredibly low, even for newly sprouted seeds, you could probably bump it up to 300 or more no worries, bugbee even says you can give seedlings 1000+ with a perfectly optimised environment. 

Edited March 29 by MindSoup

[GSZZ]

6 minutes ago, MindSoup said:

And the spectrum, below 20% blue will cause wider internodal spacing and having a lot of far red/ir can do the same. Think t5s and halides and how they're better for veg than HPS. 

 

49 minutes ago, The Villan said:

Hello after reading the thread from 2016

 

I only didn't mention spectrum because Villian referenced the thread I'd wrote years ago where I talk about spectrum - and he's using a full spectrum fixture that has, iirc, atleast 30% blue.

 

[MindSoup]

I wasn't  trying to tread on your toes or anything, I'm just adding to the pile for anyone else looking in that's interested , I doubt anyone will be arsed to find the old thread, especially as searching still doesn't really work. 

 

Of course spectrum and intensity aren't the only thing that effect a plants growth/structure/genetic expression either but that's a whole different rabbit hole. 

[inceywinceyspider]

I love having the light right up the top of the cab it works excellently, the further the light is the more even it is in depth so with a little plant you could have almost the same intensity from the top to the bottom. 

 

Flowering is the same really the further the canopy is from the light the more even the light is in all dimensions.

 

Seriously throw away the hangers.

 

[The Villan]

1 hour ago, GSZZ said:

Its not about how far away the fixture is to the plants, but the amount of light they're receiving. I like to just hang my lights as high as they'll go and adjust the PPFD with the wattage accordingly. I actually think plants stretch more when you continually keep raising the fixture.

 

110 ppfd would be a bit low for me tbh, I start at 250ppfd.

Thanks @GSZZ answers my question perfectly.

 

Edited March 29 by The Villan

[GSZZ]

54 minutes ago, MindSoup said:

I wasn't  trying to tread on your toes or anything, I'm just adding to the pile for anyone else looking in that's interested 

 

How would that be stepping on my toes? I didn't think you were anyway dude, I was just stating why I hadn't mentioned it

[The Villan]

1 hour ago, MindSoup said:

 

@The Villan 110ppfd in incredibly low, even for newly sprouted seeds, you could probably bump it up to 300 or more no worries, bugbee even says you can give seedlings 1000+ with a perfectly optimised environment. 

Thanks @MindSoup adjustments shall be made.

[The Villan]

20 minutes ago, inceywinceyspider said:

I love having the light right up the top of the cab it works excellently, the further the light is the more even it is in depth so with a little plant you could have almost the same intensity from the top to the bottom. 

 

Flowering is the same really the further the canopy is from the light the more even the light is in all dimensions.

 

Seriously throw away the hangers.

 

I think we are all on the same wavelength cheers @inceywinceyspider

[The Villan]

Just to add, in my book of settings etc I remember copying down that for seedlings between 100 and 200 was in the range. I was erring on the lower side just to make sure. I shall be making necessary adjustments in about 20 mins

Have always done seedlings on 24/7 is that ok or do they behave just as well on 18/6 with a nice kip for 6 hours ?

ps. they are all above soil and about 1 and a half inches tall.

 

Edited March 29 by The Villan

[sweettooth]

interesting thoughts

 

ive now got a 2.2 m high tent,  I tend also to keep my lights up high and fixed but I could lower them and turn them down and save some pennies. why burn all the leccy when one could lower them and turn down the juice?

 

@The Villan why not lower the lights soe more??

 

I love my T5s, haven't moved over fully to led in seedling and early veg yet

[The Villan]

@sweettooth lowering the light would I think give more warmth to the root riots and probably dry them out a bit quicker which is what I don't want m8.

[Goohfy]

Move the lights you’ve answered your own question that’s why they go up and down.Just keep them at the recommended height for light.peace Goohfy.