Seedling leaves turning yellow and curling up. Need advice, please. With PICS.

This is my first grow (second if you count the seedlings I killed in less than a week from underwatering) but I have done quite a bit of research and felt that I was prepared. Apparently, I was wrong.

Here is a bit of info on my set up:
Strain: Kerala x Skunk (free seeds)
Age: 7 days from sprouting
Grow medium: rockwool and hydroton
Hydro: top-drip irrigation
Nutes: GH Flora series
Feeding/water schedule: on for 30 minutes every 2 hours (1/16 of recommended amount)
Light: 2 x 23w CFL 5000K kept 2-3 inches from tops
Temps: range from 68-84F but usually in the mid to high 70's
Humidity: range is 45-65%
Res temp: 70-75F
Water source: purified from store or tap water run through a Brita filter and left out over night
pH: I try to keep it between 5.0-6.0 but all I have is the liquid test kit and it is hard to read. My meter should be here in a few weeks.
Air movement: One exhaust bathroom fan (50CFM) and 3 computer fans for intake. Also have a small oscillating fan.

Other info:
*I rinsed the holy hell out of the hydroton and net pots before use
-first with 10% bleach
-then ten times with tap water
-soaked in pH'd water
*I washed the tub and tubing with 70% Et-OH
-including running the Et-OH through the water pump*I have 2 foot long airstones to circulate and oxygenate the water

Things I suspect could be the problem:
*I tried to salvage one of the first seedlings I sprouted by putting it into one of the net pots just to see if it could spring back to life. I think it started to rot. The rockwool around the stem was kind of brown. What I have done to fix this issue:
-removed the dead seedling along with the hydroton and net pot it was in
-flushed other seedlings with 3% H2O2 (didn't have any stronger)
-cleaned res, airstones, water pump, and irrigation tubing with 70% Et-OH
-included 1 cup of 3% H2O2 in res when I refilled
*I have read in other forums that yellow, curled upwards tips can indicate a Mg defficiency, but I didn't think seedlings needed nutes at all for the first two weeks. Can someone either confirm or refute, please?
-I bought some epsom salts anyway and added .5 tsp/gallon yesterday (no change 1 day later)
*I have also read it can be a sign of over watering, but there is no sag to the leaves. They are curling up.

The upward curling of the tips of only one (Edwina) of the seedlings began 2 days ago, the other (Patsy) looked healthy and happy. Edwina had a root about an inch long out of the bottom of the net pot and has not grown much since the yellowing and curling began. Although, her second set of leaves got a little bigger. Patsy root grew twice as fast until she started showing the yellowing and curling. Can someone please help me?! Any advice will be much appreciated (also, this is my first thread, so please be kind).

think u need some nutrition now a low ppm , does that tap water go thru a sofener b4 it gets to the britta ? if so no good , im not vry versed on hydro but i know plants need some sort of food and rockwool and hydroten has 0 . did u wash that rockwool in ph'd water ? think it has ph probs to start with . good luck ,check in the hydro forums as well .

Thank you for the quick reply. The tap water does not go through a softener before the Britta. After filtering, the water has 95 ppm-which I think makes it moderately soft already. I soaked the rockwool for 48 hours in pH 6 water before I put the seeds in. I will also add nutes up to 1/4 the recommended dosing. Thank you, again.

Seedlings will survive for a while without nutrients, but they won't look good. To some "well versed" people it means they don't like nutrients. In hydro, you could even feed seedlings with full strength (1200-1600ppm) and it wouldn't nute burn, they're just more sensitive to problems when you do something stupid. People are just superstitious about things they've read.

95ppm is relatively soft. We have 550ppm water coming out here.

First thing to check with hydro is PH needs to be 5.8.you can get pretty close with any tester.
Your water seems a little on the warm side needs to be 68* give or take 2*.
Water level should be up to the stalk just a little below.
Do you have any light leaks?
You probably already knew this.
I would make up a new nute batch in a different bucket with lite nutes.
I waste stuff changing out my res so often,but it straightens out a lot of problems for me.

churchhaze said:

Seedlings will survive for a while without nutrients, but they won't look good. To some "well versed" people it means they don't like nutrients. In hydro, you could even feed seedlings with full strength (1200-1600ppm) and it wouldn't nute burn, they're just more sensitive to problems when you do something stupid. People are just superstitious about things they've read.

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i know this much, if u start a seedling at 1200-1600ppm, u stand a good chance of frying the shit out of it .

nameno said:

First thing to check with hydro is PH needs to be 5.8.you can get pretty close with any tester.
Your water seems a little on the warm side needs to be 68* give or take 2*.
Water level should be up to the stalk just a little below.
Do you have any light leaks?
You probably already knew this.
I would make up a new nute batch in a different bucket with lite nutes.
I waste stuff changing out my res so often,but it straightens out a lot of problems for me.

Click to expand...

When you say light leaks do you mean can any light get to them when they are suppose to be in their dark cycle? The cabinet is pretty sealed but I have opened it up right before bed to check on them. The light in my room is from CFLs so I figured since they have to be within 6 inches from the plant, it would be fine.

I will try putting a small container of ice in the res to see if I can get the temp down a little. I also added nutes at 1/4 the strength. I thought the cotyldons would yellow first if they were starving. They should have some food though, I guess.

Thank you for the help

churchhaze said:

95ppm is relatively soft. We have 550ppm water coming out here.

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Wow! That's high! Do you use a softener for your water or just buy from the store?

Lots of nitric acid based pH down.

HNO3 + CaCO3 -> Ca(NO3)2 + CO2

So I use a little less Ca(NO3)2

hepzibah said:

Wow! That's high! Do you use a softener for your water or just buy from the store?

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You are right, this is why it's suggested to start lower in my opinion. A big plant can easily recover if you do something wrong, but if you work your way up from half strength, you risk less like say for instance you use too much N. I guess the advice is to scare people away who just want to keep feeding their plants when they don't need more. I think this is a bigger worry for soil growers who can't maintain a steady ppm.

In nature, soil doesn't start off nutrient poor and then become nutrient rich while the plant is growing, it's the other way around. When a seed falls in soil, it's nutrient rich and then slowly becomes nutrient poor.

pinkjackyle said:

i know this much, if u start a seedling at 1200-1600ppm, u stand a good chance of frying the shit out of it .

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not all soils are nutrient rich to begin with , and the micro beastys keep soil healthy , bacteria and fungis in the soil feed the protizoia that feed the nemitodes that secrete readily available nutrients and micro nutrients and loosen soil and keep it healthy so no need to keep a steady ppm to feed the plant . u feed the soil when growing organic and all is gravey

Its too hot raise the lights.

*BUDS said:

Its too hot raise the lights.

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Will that make the leaves that are yellow recover or are they pretty much toast? If they are toast, should I cut the yellow parts off? I am a little worried about them because they are so small. I hope they make it.

I can't imagine keeping a high powered light cooled. I just have two little cfls. Maybe I will start freezing bottles of water to keep in there. I thought I had a pretty good fan system going.

I have raised the lights, added a little epsom salts and nutes (total is 1/4 concentration now), pH is between 5.0 and 6.0 (best I can tell with color solution). My little plants are still not growing! There has been NO GROWTH in 5 days. The roots have not grown a bit. I also cut back the watering schedule to 30 minutes 4 times a day (3 while lights are on and once while off). I also cut the brown leaf tips off. Nothing seems to be working. IS THERE ANY MORE ADVICE? Please help!!
Plant 1




Plant 2


All of my set-up info is in the first post of this thread. Please somebody tell me if my babies are going to make it!!

*Update*

Still no significant growth. There might be a tiny little bit of growth but these little ones are nothing like other 12 day old plants I have seen. Any help would still be appreciated.

ok so, couple guesses based on your op. lights too close- baby plants will burn easily. nute burn- if your giving them more than 150ppm its probably too much considering they are so small. overwatering- rockwool should be damp, never wet. once thy get a little bigger they will drink a little 1x1 rockwool cube dry in a few min, till then, saturating a rockwool cube is one of the easiest ways to kill a plant i know of. improper res temp- 75 is too high esp since your overwatering. ph- 5.5-6.2, (i try to keep my res 5.8-6) 5 is too low tho, prob not a disaster but will start to lockout a bit. hth, gl&hf

ok so checked gh feed sched. if your feeding 1/16th of the seedling rec its def not nute burn. 1/4 would be @ 100-150ppm which should be safe.

1itsme said:

ok so, couple guesses based on your op. lights too close- baby plants will burn easily. nute burn- if your giving them more than 150ppm its probably too much considering they are so small. overwatering- rockwool should be damp, never wet. once thy get a little bigger they will drink a little 1x1 rockwool cube dry in a few min, till then, saturating a rockwool cube is one of the easiest ways to kill a plant i know of. improper res temp- 75 is too high esp since your overwatering. ph- 5.5-6.2, (i try to keep my res 5.8-6) 5 is too low tho, prob not a disaster but will start to lockout a bit. hth, gl&hf

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Thanks. I had the CFLs about an inch away from their little tops at first then moved them about 2 inches away. They never stretched so I thought that was a good distance. Since I have moved the lights farther away, there hasn't been any more yellowing (hasn't been any less either). Maybe I will bring them up another inch or so. I just wish they would start growing again.

I am also feeding/watering 4 times per 24 hours. 3 times with lights on, once with lights off. Each sessions is 30 minutes. Should I back off to 3 times per 24 hours?

well when they get a little bigger that will be fine. the thing is when they are realy little they just dont use that much water and if you saturate the rockwool cubes the roots cant get any o2. i start plants in 1x1 rockwool cubes, the way i get them wet at first is to dunk them then shake the water out so its just moist. then i add a few ml a day with a pipet till they get a little bigger. if you underwater, it will be obvious realy fast and they will recover very quickly when you give them more. if you overwater you will prob get rr and thats not so easy to fix. for the first couple weeks they realy only need a few ml a day. just make shure theres air in the cube so you dont get rr.