Need some help with my seedlings

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grottawa

New Member
Hi,

I have been following this forum for awhile and since everyone here seems so nice and knowledgeable I'm hoping someone can help me this poor newbie out lol.

So I'm new to indoor growing. I have a 3x3 tent with 4 inch ventilation and filter hung inside the tent, passive air intakes at the bottom, humidifier and clip on fans etc.. Everything seems to be perfect. Temp 74 and rh at 60. I'm using canna terra pro plus soil.

Here's my problem. Usually outdoor i plant straight to soil but for my first indoor grow I decided to get adventurous and germinate in rockwool as everyone swears by it.

Fast forward two weeks and the seeds had sprouted with roots exposing on the bottom. The rockwool looked real brittle so I decided to plant them in their 5g soil fabric pot forever homes and gave them a ph'd watering no nutes.

So I am using a mars hydro tsw 2000 LED light. The instructions that came with it said to hang it 30 inches above seedlings. I learned through a YouTube video just yesterday that the light needed to be dimmed by 50-70% and hung at 30 inches as the light is too strong. Would have been nice if mars hydro provided that little tid bit in the package lol.

Here's my question lol. Are these seedlings (attaching pics) burnt from the light or is it a watering/root problem caused by the rockwool being planted in soil? Can they be saved or am I starting over?

Does anyone have experience with this light and could possibly provide the heights and dimmed wattage they used from seedling to flower?

If anybody could help that would be greatly appreciated.

Thank you
 

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SPLFreak808

SPLFreak808

Well-Known Member
That does look like light bleaching, Mars hydro actually recommend 10w/ft2 for seedlings with that light, that does sound on the lower side but you will have plenty of time to bump up power as they grow.

Your at 30w/ft, that power level with decent leds can flower small plants easily.

Dim that panel like hell and work your way up as needed?
 
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grottawa

New Member
Thank you for the reply!

I'm really bad at math so if I dimmed the light from 300 watts down to 100 watts and kept it at 30 inches that equal 10w/ft²?

When should I begin increasing the power after theyve recovered? Should I keep it 30 inches the whole time or begin lowering it at some point?

The instructions that came with the light says during flowering 12 to 18 inches. Would that not burn or bleach the flowers id it can do it to seedlings at 30 inches?

Thanks again
 
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Frigault

Well-Known Member
For your futur reference never follow someone or some company technical advise if you don't have the exact same set up chance are something will go wrong... For future reference start far and lower light slowly ti you have it your sweet spot. The same light distance with a fan blowing cool air over your seedling could have been okay and without cool air blowing wasen't. If i put mars hydro light in the box half the height of your tent result could laso be worst and in a open room totally fine. Use touch feeling next time if you think the heat sensation is warm then your plant will react... Your plant will heal up and those leaf will die.. But yeah don't get too caught up with mimicing what people do. What works for one may not for another... Always used progressif strategie and wirk your way up there. Its a l ways easier to fix a probleme when its a lacking of something then when its being overdone... Till yiu fine your sweets spot.. There are never an exact mesurement everygrow room environment is diffrent
 
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grottawa

New Member
Thank you.

I think you hit the nail on the head.

I will use better judgement from now on and not rely on vague general guidlines from the manufacturer lol.
 
SPLFreak808

SPLFreak808

Well-Known Member
Thank you for the reply!

I'm really bad at math so if I dimmed the light from 300 watts down to 100 watts and kept it at 30 inches that equal 10w/ft²?

Width x depth = square footprint. 3x3=9
Your light at full power draws 310w
310÷9= 34w/ft2
90÷9= 10w/ft2
120÷9= 13w/ft2

Let's just ignore cubic footprint for now, yes it will lessen overall light the higher it gets but we generally ignore it due to square footprint being more important during veg (more space).

When should I begin increasing the power after theyve recovered? Should I keep it 30 inches the whole time or begin lowering it at some point?

Eventually they will green up and start stretching with bigger leaves, you can slowly bump up the light from there, keep in mind when you go borderline too much light, it can take cannabis up to a week to actually show any damage so keep your eyes open.

The instructions that came with the light says during flowering 12 to 18 inches. Would that not burn or bleach the flowers id it can do it to seedlings at 30 inches?

As they grow into the environment they will get used to it until/if they hit a limiting factor (temps,c02,nutes,light,etc)

From MH's website,mars_hydro_TSW-2000_recommend_coverage.jpg
 
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Frigault

Well-Known Member
Cfl uses a good spectrum and are great for seedling. I used about a week then i put under with my veg light quite high and lower it within a week (i cannot dimm) and i let my pkant grow to a certain height. Were my hand tell me its a goid feel (if i were to put a heat sensor it would read 22-25. And i look plants reaction at this point if light seems far from the plant i blow a fan above the canopy and between the light if there isen't any burn or bleach temps seem normal at tip of canopy then i consider this the sweet spot for maximum par input..
 
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grottawa

New Member
Great response! Thank you so much!

See that's why I came here for help. I'm actually learning something....even if it is just basic math lol
 
F

Frigault

Well-Known Member
There is always something new to learn even for advance grower... Always a new trick a new tech... And looking back at thing you think you already know often show you small detail you missed... I judt bought my mom a mars hydro. Since i've got experience and went to school for this. I've always had atleast one plant with me for past 20 years and lately every year she's been trying to grow. Get me to start them. Then went she comes visit and sees my plant she cries. Litterally tumble in tears and ask me to help her... Its more then likely alwats to late. And i know her light source is the probleme and she can't afford one. So her next plant will be okay this time...
 
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grottawa

New Member
Yeah I've always relied on the sun so figuring out thisblighting was a little trickier than I expected lol.

I thought i was set and ready to go. My grow tent has ideal conditions.....Great temp, airflow, humiditiy. Only thing i didnt count was having to use math lol. Made sure i got the right light for my grow space size just wasn't smart enough to realized said light needed to be dimmed down so much to start.

Thanks to everyone on here. Great responses and tips. Hopefully I get this grow on track from here on out but I'm sure I'll mess something else up eventually and be back here asking for all your help again lol
 
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