Why am i killing my girls

[Jimi]

Greetings everybody and thank you for letting me join.
Its my first post on this forum so here we go.

Im back with the hobby after more than 15year break and mildly said its been bit of a rocky start.
My skills are bit rusty and i cant figure out why am i killing my girls so any help is appreciated!

Here are some specks:

2 NorthernLights on week 3
60cm x 60cm x 160cm grow box
100w COB led about 10-15cm from plants
Lights: 24h regime
Im using special seedling soil (as its not over fertilized) + vermiculite + perlite mix in 12L canvas pots.
Havent given any nutes
Temps range from 20c to 25c
I installed my old 350m3/h fan with passive intake blowing on plants (i know its way too big but at the moment its all i have).
+ on the floor there is small bathroom fan circulating the air around the pots.

Been watering with 6,5 PH and just today tested the soil which was 6,8. BUT i think this part i messed up cos i might have under-watered them. Its my first try with soil and still trying to figure out watering schedule so i kind a left them in peace and watered them hmmm... not so regularly meaning the top soil was always pretty dry.

As you can see from the pic,
- leaf tip is dying off,
- everything is turning yellow
- and the growth rate is (at least what i remember from hydro times) way toooooo slow, they should be much bigger

Could it be underwatering or wind burn from the 350m3/h fan (passive intake blowing directly on them)?
Ps. or could it be stress related? After transplanting, i had to finish building the brow box so during the day they were sitting on kitchen table for 4-5 days tho transferred them to the grow box for night.

Guys, what do you think and what can i do to help them get passed this?

Again, thank you in advance for any guidance you can give!

Peace & Bless!
Jimi

 

[hecno]

100w COB at 10 to 15 cm . I would say you are cooking them . I run my cobs [ 50 watt - [ 9 ] 36 in -90 cm - from seedlings .

 

[Jimi]

Never used COB before and read that these can be much much closer than HPS lights, 10cm from plants would be ok but your comment makes sense. Will go adjust the lights asap.

Thank you for the help.

 

[Olderfart]

Never used COB before and read that these can be much much closer than HPS lights, 10cm from plants would be ok but your comment makes sense. Will go adjust the lights asap.

Thank you for the help.

I agree with @hecno re. the cobs. Different designs, different distances, but if your cob has a lens in front of the led, I think you need to be a lot further away. The bleached tip on the highest leaf is the symptom that concerns me re. the cob. What does the manufacturer recommend?

Depending on what is in the soil, you could also be starving her or locking her out. The new growth has more green where it is not bleached, and the lower fan being eaten may suggest that nutes may be too low. Just a guess on my part, she is in pretty rough shape. The plant in the photo does not look underwatered to me. A plant that size and condition would take a long time to dry out a 12 liter pot.

Sad to say, but if she was mine, I would be thinking about starting another seed, but perhaps not with the same soil mix. If you go this route, your safest bet would be to use the same soil and nutes as someone here has used with success.
Good luck with it.

 

[Proph]

No light should be 6 inches away from the plant and on for 24hrs. Hps distant is 24-36 inches away.. Cob distance can be 12-24, which is what they mean by much closer. They don't mean 3-5 inches away.. Pop another seed and keep your light at least a foot away if not more

 

[Jimi]

With the distance.... i think i got inches and cm mixed.. damit I have to test soils EC tomorrow but i specially chose soil with minimun extra fertz as i understood that autos prefer this type of soil. Country where i live, they only sell heavely fertilized soil. The one i use now was only one i could find so guess have to stick with it.

But what you think, would she recover from this or would it be better to start it over and if she recovers, would it effect the end result?

Bless!

 

[Jimi]

The new growth has more green where it is not bleached, and the lower fan being eaten may suggest that nutes may be too low

You were right. I tested EC and its only 280ppm. I have some old crappy chart but if im reading it correctly 280 is way to low...

 

[Simplicio]

As others said, you are frying those plants.
If those were my plants, the LED would be much further away.
Seedlings don't need much food, so I doubt 280 ppm is causing problems.

 

[Olderfart]

With the distance.... i think i got inches and cm mixed.. damit I have to test soils EC tomorrow but i specially chose soil with minimun extra fertz as i understood that autos prefer this type of soil. Country where i live, they only sell heavely fertilized soil. The one i use now was only one i could find so guess have to stick with it.

But what you think, would she recover from this or would it be better to start it over and if she recovers, would it effect the end result?

Bless!

Re. soil, if you are ok with trying salt based nutes, you can almost certainly get peat, vermiculite, and gypsum in your local garden suppliers and put together the mix recommended by Dr. Bruce Bugbee here:



(sorry about the oddball age warning, but I checked the link and it worked for me)

This video of his covers more than just the soil mix, but it is all worth a listen. The guy knows his stuff, and his suggestions are based on serious research science.

As to whether she will recover, others here have more experience than I do, but in my relatively noob opinion, if she does, she is unlikely to produce much. She doesn't have much leaf power left so even if she recovers, by the time she by the time she does, she will still be badly stunted and the auto clock will be run a long way down. If it were me and I had the seeds, I would get them soaking and figure out my soil supply. Just my two cents of course.

Good luck with your decision, and I am sorry to see your girls is such sad shape.