What's up with this seedling?

Hey guys, just started some seeds and one seedling is looking a little wonky.

I started the seeds in rockwool at .7EC (including .3 from my tap water) about a week ago, and then I topped up yesterday with .6EC (including .3 from my tap).

Not sure if it’s under fed or what, I honestly normally start lower EC and still see green seedling. Might not be food related.

The other 4 are ok, though one other seedling kind of starting to get the same color tips maybe (very feint).

Any ideas?


Did they dry out a lot between watering?

What pH?

I don’t usually feed them until they are a little bigger.

What have you done differently this time as opposed to last time?


pH between 5.5 and 6.

Normally I guess I feed less but had some problems with them sort of stalling after the first week.

I’ve had this happen a couple times where there are weird spots on one or two and I usually just throw them out. Reasoning being that if the other 4-6 are fine then this one is probably weak in some way and will be finicky throughout the grow.

However, I can’t afford to pitch that one this time and I’ll have to actually figure it out :thinking:

I actually weigh each cube on a scale at this stage and none of them were less than about 35% of their original weight.

PS do you start your seeds in rockwool? If you don’t feed them right away and they do fine, that might be an indicator I over ferted them

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I start mine in the peat starter pods and had success, unless I bury them to far. I did nothing but water mine for the first few weeks. However, I am a new grower.


how did you germinate them

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Seed In the rockwool cube, in a humidity dome. Soon as they appear to sprout I move them to a tray with no dome.

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The weighing is an interesting idea.

I use promix with no fertilizer charge. I have had (I think) pH swings when letting things get too dry. The pH of the mix is very low so if they’re not wet with a higher pH water/fert it gets too acidic.

But it could also just be a weak runt also.

I dunno man.

Edit - I just googled rock wool starting pH and it says 8! You might have the opposite of the problem I’m describing

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I’ve always used a wet paper towel let the tap root get to about 1-1/8 inches then take potting soil put it in a small pot push my finger in the center to just past the first knuckle then drop it in till it just covers the seed lining gently push soil over it the water it but don’t pack the soil down so air is inside the hole put it in direct sunlight so as soon as it breaks ground its already aclamatted to natural light so you save time they always seem to come up bright green and the stem turns red it sturdy"s quickly

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i also put a small cup under the pot with water so it can keep the soil damp then take it away after the seed ling is about a half inch tall alway have healthy seedlings haven"t lost one yet in 3 years started all 12 of mine this year the same way all are healthy and strong today

So I normally soak them in 5.5 pH solution to mitigate that, but apparently it’s not enough…

I used an oral syringe to remove about 10ml or water from the cube:

pH 7.0
EC 1.0

Both too high. I’m thinking maybe soak them in 5.5 tap water…

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Thanks for the info. In start in rockwool cubes so that I can move them to larger rockwool cubes. Never grown a plant in soil. I grow in bedrooms so bugs/pests etc. aren’t an option. I’ve never had a pest in any of my grow rooms so I’ll probably stick to hydro/rockwool although I do think it makes some things unnecessarily difficult.

heres the result i get


Yes that sounds like it could make sense. Maybe rinse them out a couple of times.

All the best


i use bottled water to start them some tap water has too much clorine and floride

Yeah I thought that would be enough too. How long do you soak? I soak my rockwool in 5.8 for 24 hours. Not saying that is what the problem is but to me it kinda looks like a ph issue. I actually had one last year yellow up and die like this and of course my ph I soaked in was off. I’d give it until that third set comes in and start dosing nutes and see if it pulls through but that’s just what I’d do

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Yeah I probably didn’t soak long enough, maybe 15 minutes… When I topped them up it was with 6.0 pH, I should have used 5.5 again.

Next time I’ll soak longer and then possibly rinse them with a fresh solution. After the initial soak I’ll just use pH’ed tap water if they get dry.

I’ve noticed I get better germ rates and seedlings sprout faster if I soak with mild nutrients (.3 EC of nutrients).

I’m not sure, but in rockwool since there is no nutrition, I think having some nutrients in the cube signals the roots what to do. I’m not 100% sure on that, but Grodan says it’s Ok to soak with mild solution and also the rockwool guy I follow Everest Fernandez (aka Just For Growers) uses mild solution to start them. I’m not sure it makes a difference… I definitely should not have added more nutrients though.


This last time anyway 2 sets of leaves and 3rd node on its way before I gave them anything (feed). I had pH swings and overwatering and the roots dying off or the whole thing with solo cups. Back to domes and trays. Not that there aren’t other ways just trying to do it easy and cheap without wasting seed.

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Yeah I cant speak to that. I’ve never used any amount of nutes In my soaking solution but i might give that a go next time. My biggest problem has been not having them warm enough so they dont wanna move and are just dead in the cube. I might try a light nute solution my next cycle in a few months

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Yeah yeah me either. I wait til the third set starts coming in