Please help 1st timer diagnose deficiency

Ok, so I sprouted 5 beans of Purple Cheddar and 3 Bagseed from 2015. Germinated in water for a couple days and then paper towels til I got them planted in 1.5" rockwool cubes in a jiffy pot tray. Jiffy humidity dome, heating mat, 12" 3500k t-8. Initially had problems balancing out temps, humidity, and watering schedule (distilled 5.6 pH water w 1/2 drop of superthrive per cup). Lost a couple seedlings, but realized too late to supplement with calmag. A non-oscillating circulation fan blowing too directly wind burned the survivors from the damping off plaguing my earlier humidity/temp probs, so I that after their 2nd week the remaining 2 seedlings were: 1 "Purple Cheddar", and 1 "Bagseed 2015".
I picked up a 2x4 Gorilla grow tent to make environment stabilization easier and i have it set up w (2) 23-watt 5000k cfl's, (1) 2ft 6500k t5ho, heat mat, circ fan and exhaust, and a humidifier. I've been able to keep consistent temps of 78-80 F, and 55-70% humidity.
I started feeding at 16 days w 1/4 strength GH 3-part Flora w calmag, mixed w 1 gal distilled water as follows:
GROW -10ML
MICRO -7.5ML
BLOOM -2.5ML
BIOROOT -5ML
CaMg+ -5ML
...adjusted pH to 5.63, 1194 ppm for 1 gal, then diluted to 1/4 strenghth and got: pH 5.84, 506 ppm. (Next time I'll dilute 1st, then pH!)
Same night, I soaked 3" Rockwool cubes in diluted nute sltn ph'd @5.64, 594 ppm.
I also set them both to 24hr light schedule vs 18/6 they'd been getting since germination to hopefully speed up growth (learning curve) bc of availability of nutes now.
Purple Cheddar had been slightly lime-green due to deficiency, but seemed to be improving, while Bagseed 2015 was looking fine, despite the healing leaf tip burn from heat stress early on.
2nd hand watering/feeding 2 days later (pH 5.81, 794 ppm) on day 18. Transplanted into 3" cubes on day 19

The cotyledons are now very yellowish (mb tb expected), but accompanied by the other lower leaves beginning to yellow on both, I'm concerned and need help saving my last 2 seedlings. Is it transplant shock? Is the droopiness and yellowing bc of root stress? Do I just wait it out til roots grow into their new cube from starter cube? I wasn't sure, but doubtful... leaning more towards a nute/water deficiency due to lack of uptake via roots. Although I know that less is usually better when feeding nutes to avoid burn, I thought mb top feeding wb good idea to buy them time to grow into new cubes. This was yesterday, so I top feed them abt 35 ML's of the 1/4 str nute sltn each. I repeated same thing 6 hrs later, then again this morning. Today is day 22 above ground and I'm trying to keep them growing.
Any advice, insight, suggestions, or observations are very much appreciated. Please don't be too hard on me though, besides last year's garden tomatoes I don't have much growing experience. Cannabis growing, and hydro in particular, is a learning curve. I just need a lil coaching on leaning into those curves. BTW, I'm still figuring out what the best system for me w/b, hence the 3"cubes: to buy me some time in order to decide on a system and finish my grow room. I'd rather save that discussion for a later time, though. Please help me get these girls thriving!
Peace Out to all Cannafriends,
~Cannasseurrr

I don't have much experience with rock wool but those guys look underwatered and overfed.

For seedling like that I aim for 300-400ppm max. Plants will show all sorts of funky deficiencies when you let them dry out too much too often. Happens to me all the time with my seedlings once they get too root bound and they dry up within a day or two. Your ladies kinda look the same.

Sounds like you feed them 3 times per day though? what's your watering schedule and what was it before you transplanted? Could definitely be transplant shock as well

The burned tip on the one lady is def nute burn

This was Bagseed 2015 @ 8days, just burned (only 1/2 str superthrive w distilled)

This was Bagseed 2015 @ 8days, just burned (only 1/2 str superthrive w distilled)

Sheik_ thanks for the reply. Watering schedule was every other day, as the 1.5" cube wld start to get light/slightly moist. I agree that this was insufficient watering, but the yellowing began before real nutes @ day 14, prior it was just 1/2 drp of Superthrive in 8 oz distilled... I'm not disagreeing w you, just trying to think it through. The beginning of limey green on Purple Cheddar in particular is what made me realize that I hadn't even given them calmag, much less N-P-K. They looked improved 2 days after the 1st feeding, so i watered w same nute sltn @ day 16, cube was moist not dry so I did a 3 second dip to half-way down cube (remember I had 3" cubes soaking, so I didn't want to fully water. My thinking being that cube s/b more wet in order to promote roots reaching and growing into it... So since yesterday, I've been doing 3 hand waterings a day to keep the root zone moist, not soaked. Again, to promote root growth. I'm realizing that it's a fine line to walk, just not sure if there's a better way?
... Anyways, ask some more and keep responses coming! I appreciate the insight.
~Cannasseurr

Cannasseurrr said:

Sheik_ thanks for the reply. Watering schedule was every other day, as the 1.5" cube wld start to get light/slightly moist. I agree that this was insufficient watering, but the yellowing began before real nutes @ day 14, prior it was just 1/2 drp of Superthrive in 8 oz distilled... I'm not disagreeing w you, just trying to think it through. The beginning of limey green on Purple Cheddar in particular is what made me realize that I hadn't even given them calmag, much less N-P-K. They looked improved 2 days after the 1st feeding, so i watered w same nute sltn @ day 16, cube was moist not dry so I did a 3 second dip to half-way down cube (remember I had 3" cubes soaking, so I didn't want to fully water. My thinking being that cube s/b more wet in order to promote roots reaching and growing into it... So since yesterday, I've been doing 3 hand waterings a day to keep the root zone moist, not soaked. Again, to promote root growth. I'm realizing that it's a fine line to walk, just not sure if there's a better way?
... Anyways, ask some more and keep responses coming! I appreciate the insight.
~Cannasseurr

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So ya it sounds like you underfed to start....Just using superthrive til day 14. For seedings you'll need more than that, at least a feed on 200-300ppm every few days after the first leaves have shown.

Now your overfeeding by a slight amount judging by the slight burnt tips.

You're doing a great job of being attentive and keeping temps and humidity perfect just gotta dial in your feeding strength and watering.

I'd say keep up what your doing with the watering, make sure they have a nice even moisture content, not too wet but don't let them dry out too much and lower your ppms slightly to say 300 and just be patient. It will take a little time for them to recover. Don't go chasing nute deficiencies like cal/mag. The GH nutes your feeding have plenty of it, especially for seedlings like you have. I use GH 3 part all the way through my grows with no cal/mag. You're plants are just a little shocked, you just need to baby them back to health and be patient. Chasing nute problem will just lead to more problems.

Hope this helps

No problem. I'm sure lots of people will chyme in. Hopefully someone with more experience with rock wool.

Fyi I use gh 3 part and never go more than 700ppm at max strength. A lot depends on strain but that's one of the reasons I'm thinking over feeding. For little guys like yours i use 300ish. No more than 400 for sure.

I am seeing overwatering and a slight overfeed too. Only give them water when they need it...the operative word here is need. In a weeks time or so you will see them perk up.

Over watered.

shaughnny said:

I am seeing overwatering and a slight overfeed too. Only give them water when they need it...the operative word here is need. In a weeks time or so you will see them perk up.

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Shaughnny, thanks for the input. Now can you help me understand why you think so? (I want to learn, so wondering what observations lead you to believe this). Do you have experience w rockwool? I've heard it's hard to overwater in this medium, and concerning watering I've been erring more on the side of "too little" than on "not enough"... watering 3x/day only began yesterday, and technically it's 3 including this morning (24 hr period). Comparing mine to a top-feed (drip)hydro setup with my plant size, isn't 35 ml (about 2 tablespoons), every 8 hrs conservative?
More input please!
Stay Medicated,
~Cannasseurrr

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RetroGrow said:

Over watered.

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Thanks for the input RetroGrow, kindly see my response above. I'd like to understand your thoughts behind it, if you wouldn't mind elaborating a bit... Ty!
Stay Medicated,
~Cannasseurrr

Rockwool stays wet for a long time and its suffocating the roots. Next step is stem rot at the point of entry. Ive never heard of dropping seeds into straight rockwool. In my opinion it holds water too tight

To be politically correct the problem is lack of oxygen to roots. Next time dont use rockwool or let it dry out. I use a mineral soil to sprout in. Rockwool is similar in chemistry but its spun like a sponge. Your roots need more air if theyre gonna be that wet. Cotton balls are better than rockwool and its easier to find. Instead of rockwool just use rock!

@Emmay_ I've been searching for answers as well, and overwatering/underwatering seems tb the cause. Rockwool is a very common propagation medium for seedlings and clones, although to be clear, I germinated in water 1st then transplanted to rockwool starter cubes. The starters have holes in them for seeds and all. I agree that it's different and poses its own set of challenges, but I think the fault is more in my handling of the medium than of the rockwool itself...On to more research, and Thanks for the input!
~Cannasseurrr

The fault in those rockwool cubes are their inability to release moisture. Put an empty cube under it or something to get more air under there

Hello all,
so i stopped watering after yesterday's afternoon feeding, and spread both cubes further apart to increase air circulation and dry faster. No water... this morning they were looking droopy and still Limey yellow.This afternoon, they are starting to perk up but look like they ARE burned... D'oh!
On the bright side, I see roots coming out of the bottom of the 3" cube! I'm just about done setting up a DWC rig. Pics later, and I'll be starting a grow journal as soon as I get time.
~Stay Medicated

Seed starter mix is optimum for starting seeds. Lose the rock wool. Too saturated. Transplant to seed starter mix or coco, and let them dry out/breathe. Roots are drowning in those cubes. Drooping = over watered. Over watering and over feeding are the two most common mistakes, especially for seedlings. Easy does it.