PPFD: Dimmer vs Height ??

[ExNavyInSTL]

I often see suggestions that you should refer to "the light's manufacturer technical info" for what height you should use per stage of growth.

However, isn't what's really important is the PPFD/DLI?

In other words ... If a seedling requires 100 - 300 PPFD, does it matter if I get to those numbers via dimmer switch or height of light? Are both roads headed to the same destination?

I ask because I want to get ahead of lanky and tall seedlings. I know they stretch to reach light, but are they really just chasing PAR/PPFD?

I'm using a much stronger light that at 32" high, and dimmed all the way down I am getting 300 PPFD at the top of the pot. So, lowering in may case will push them into a stronger photon barrage than they are ready to battle.

I've moved them closer to 400 PPFD to see if that slows my OG Kush down.

If you look at this photo you can see the leaves are about 1/4" above the water sensor ... yesterday her cotyledon was resting on the dial. While my Double Grape has basically stayed the same for the last two days. I understand there can be canopy issues when growing more than one cultivar at a time. I see LST in someone's future. : )

For Reference:

 

[Badfinger]

I'm of the same mindset as you. Twice I tried following the manufacture's recommendation's and it burns the crap out of the cola leaves. So I just follow the PPFD guidelines to the best of my ability.

 

[2budz]

I personally leave my lights at the same height from start to finish. I sometimes dim the lights but typically run them at 100%. For seedlings the light is 24-28 inches above and they grow into it. I don't do LST only top now and in my 1 gallon pots they end up the perfect size. I am height restricted so I don't want my plants getting taller than 18-20 inches.

 

[2budz]

For reference, I run 2x2x3 tents (small I know) and I have a Mars Hydro ts1000 in one and 2 chinese 100w with Samsung diodes in the other. I typically start my plants in the tent with the 2 100w then move them to the tent with the mars just becuase they seem to bulk better in there. Works for me so far but I am going to replace the 2 100w lights probably in the next few days. Probably just gonna do an ts1000 as my plants seem to love it.

 

[Tom Bombadil]

I dont fuss with all the science when it comes to lighting. I just blast them with autocobs (24-30 inches) and see what happens.. which is usually something good!

GL

 

[ExNavyInSTL]

To, I hear ya.

Give me a few grows and I bet I stop making journals (if I finish this one :smoking.

I do like the basic perimeters of matching temps and humidity, and following some guide for correct lighting. I'll vainly admit I want to grow at least one grow where I max the plants ... that for the photographer in me. Quality is a close second. I have a feeling in the future those 2 priorities will swap out.

ExNSTL

I dont fuss with all the science when it comes to lighting. I just blast them with autocobs (24-30 inches) and see what happens.. which is usually something good!

GL

 

[CannabisMingus]

However, isn't what's really important is the PPFD/DLI?

 

[ExNavyInSTL]

The guy on Welcome to the Grow Tent (You Tube) is a minimalist as well when it come to lights and most things. He says raise em' and crank em' (my words and interpretation ). And he's a very prolific grower.

I'll get there.

I personally leave my lights at the same height from start to finish. I sometimes dim the lights but typically run them at 100%. For seedlings the light is 24-28 inches above and they grow into it. I don't do LST only top now and in my 1 gallon pots they end up the perfect size. I am height restricted so I don't want my plants getting taller than 18-20 inches.

 

[CannabisMingus]

I go by DLI. 40 ish for seedlings - 50 ish at day 12+

I use a par meter but hear good things about that app

 

[automan2]

Being a perpetual grower, I pamper every plant for 3 weeks in a veg area, then throw'em in a bloom tent where they're blasted with over 700w mixed lights...I keep everything 12-18" above canopy... runnin 12/12.....