Seedlings stop growing right after germination

[GinoTonico]

Hi everyone, this is my first time posting here — I hope I’m in the right section!

I really need help, I don’t know what else to try: I’ve already planted autoflowering cannabis seeds three times, and every time they germinate very well, grow for the first 3–4 days, and then just stop. I’ve tried using only water as well as water with nutrients, but the result is always the same. They grow to about this size and then get stuck (see photo). The leaves start yellowing right away, and the roots also stop developing — it’s as if they can’t break through the jiffy to grow outward.

Here’s my setup: professional grow box with a MarsHydro TS1000 light (I’ve tried different dimmer levels and heights, but light doesn’t seem to be the issue — I think?), 11L pots with soil (just some added perlite, nothing else), automatic humidifier set to 70% (it turns on/off automatically when humidity drops below 65% or goes above 75%), temperature inside the box stays between 25°C and 30°C. I have a fan running 24/7 for air circulation, and both the exhaust and intake fans are set to run automatically for 15 minutes every 2 hours (except when the lights go off — then they stop as well). The light is on for 18 hours a day.

I water with demineralized water and add CalMag. As nutrients, I’m currently only using Power Roots by Plagron. I also tried tap water left to sit, but the outcome is the same. As I mentioned, I tried both with and without nutrients to see if that was the problem, but no difference. I check the pH of the solution before watering using a pH tester (Ph range 5.5 - 6.5), and so far, since the plants are still so small, I’ve only been misting the soil to keep it moist — avoiding overwatering.

In the past, I’ve successfully grown 4 plants, and strangely enough, back then I was much less precise — just using demineralized water and no nutrients at all.
This time I planted 2 Epsilon F1 Hybrids from RQS and 1 Royal Automatic, also from RQS. The seedlings in the photo have been germinated for 8 days, and they’ve looked like this for 4 days already — I’d say they’re stuck too

Does anyone know what might be going wrong?

Thanks in advance to anyone willing to lend a hand!
Much appreciated!

[Mjcalifornia]

Hi Gino, welcome to the community! What kind of soil are you using? Or is it coco? I may have missed it reading through your post so I apologize if so!

[BluntForceTrauma420]

It looks like you have some kind of auto watering base on those. If correct you need to be top watering for the first week or so till the roots establish. That’s the case with any bottom watering system.

[Demonrage75]

Usually when they stop growing above ground they are growing Underground, spreading those roots out. They’ll start growing again soon.

[GinoTonico]

I am using soil TERRA PROFESSIONAL I think is a good soil

[GinoTonico]

Those wires you see are for heating, they give a little help mantaining the temperature insider the box above 24 degrees. For watering I am using a plant mister on the soil around the seedlings

[GinoTonico]

You think? Even if they are auto?

[BluntForceTrauma420]

Yeah you need to water more most likely. At this stage I use a turkey baster to water around the base of the seedling.

[Icirazy22]

With autos you can keep the soil moist at all times they like that I have been watering when my top soil dries out even if my pot is still heavy as long as you have good drainage and a good medium it should be ok you always want to water your pots all the way through just when they are small water around the base of the plant not directly at the base. Happy growing!

[Jamon8]

I only go with strong plants now. If they seem weak in the beginning, I am done with them. A 10-15 dollar seed is not worth growing a stunted plant. All the electricity, water, nutes and your time is wasted. I have never had a slow seedling turn into anything that was worth a damn.

I am about to yank a plant right now for underachieving.

[GinoTonico]

But what could be causing the leaves to turn yellow this early in the seedling stage? It’s happened to me before, but only in later stages of growth — never right away. I usually water when the lights are on — should I be doing it when the lights are off instead?

[GinoTonico]

@BluntForceTrauma420

turkey baster

I am using something like this, and I spray until the surface of the soil is watery (not too much, I am afraid to drowning them, so small). It is not similar to the effect of a turkey baster?

[BluntForceTrauma420]

Turkey baste will penetrate deeper than just spraying. You want the top 2-3 inches to get moist so the roots have stuff to expand into.

[GinoTonico]

I tried watering them using a turkey baster, but I only made things worse — after 24 hours, they looked even worse than before. I had to kill them, guys
When I removed them from the pots, I noticed once again that the roots hadn’t managed to break through and grow out of the Jiffy. That’s why they stop growing — it’s like the roots run out of space and just give up.

But what could be causing this? Why do the roots stop developing so early, and always at the exact same stage? I even tried different seeds, but the result doesn’t change.
Should I try germinating directly in the soil instead? Could the soil around the Jiffy be too wet? Or too dry? Maybe too compacted? (Though I don’t think that’s the case — I never press down the soil, I just gently shake the pots to avoid air pockets.)

I honestly have no idea what to try anymore — it’s so frustrating, and I just can’t figure out what’s going wrong.

[Geeorgeds]

Hi Gino,

I’m not 100% sure what the problem is, but you could try breaking up the jiffy (I assume it’s a coco pellet) so it just turns into loose material. I always do this. It could be that the outside is a bit thougher to keep the jiffy as a whole?

If you do that there should be no reason for the roots not to grow out of the jiffy.

So if you still have the same issue you’ll know it’s not due to the jiffy but due to watering or smth else.

[Demonrage75]

I stopped using the Jiffy plugs just bc of this reason. The outer covering of the jiffy plugs can be tough for roots to grow through and stunt baby plants. If you leave them long enough the roots will grow through the plug wall. I’ve tried the jiffy plugs with seeds and clones but have learned they don’t work great with either.

[GinoTonico]

Thank you so much for the replies!
So would you recommend trying again with the Jiffy, but removing the mesh around it before transplanting?
Or should I use the wet paper towel method and then place the seed with the taproot directly into the soil?

[BluntForceTrauma420]

I prefer the paper towel method then straight into the soil.

[Geeorgeds]

If your container is not too big you could immediately go from wet paper towel to soil I think.

Me personally, I have a small 1l pot which I fill with some soil mix. In there I make a little hole in the middle and I fill it with the hydrated coco pellet which I break up into pieces. I then put the seed from the paper towel in the coco soil. When the soil dries up I only water the sides of the pot and slowly and in steps until saturated. And then let it dry out completely before watering again. And when the seedling has grown a bit I put them in their final containers.

I do this mostly because I’m scared of overwatering in the beginning. But take into account it’s only my second grow so I’m also still learning.
Also best not to repot with autoflowers I’ve read (not sure what you are growing).

[BluntForceTrauma420]

You can do it directly to a large pot. I go from paper towel to 10 gallon pot. I learned this from a guy who does it directly into a 4x4 bed. The less you restrict the roots the better. When you have roots wrapping around in a solo cup or the like you are stunting their progress.