Seedlings ending up stunted at the same stage of growth?

[remdog]

Hi people,
Been dabbling with growing for a few years now but this year marked my first serious attempt at trying to grow some nice buds. I've been using a a large cupboard for the grow since I'm limited on space. The seeds are sensi seeds purple bud autos and I'm using a 600 watt LED light and maintain temps of 19 - 20c, RH is consistent at 40 to 55% and I have distanced the light appropriately. I've been using living soils fertilisers grow auto, flower, barley, wormcasts and frass (similar to Gaia green organics in the states) following their feed chart in a mix of canna coco Pro plus with about 20% perlite all in a 20 litre pot (5 gal US). I'm not using a tent as budgets limited, but I do have a small fan to circulate air which is not directly pointing at the plant.
Essentially this and my previous attempt have both become stunted while developing their second set of true leaves about a week from sprouting, as far as I understand the plant should develop more without requiring any feed which makes me think I may have a watering or maybe disease/mould issue?
I've also noticed a yellowing of older leaves starting with cotyledons in my previous attempt, there was also a slight twisting and curling to some of the leaves. Current attempt sprouted on the 12th this month, photos show it on the 21st and today (29th).

 

[mysticepipedon]

There's not much information here, but those temperatures are way too low. Get it up above 25 C. This alone will about double your growth rate, if the plant has everything it needs.

The last pics show a touch of canoeing, so the light might be too close.

 

[remdog]

There's not much information here, but those temperatures are way too low. Get it up above 25 C. This alone will about double your growth rate, if the plant has everything it needs.

The last pics show a touch of canoeing, so the light might be too close.

Ok thanks gonna try and keep temps up while also letting air in, in theory everything should be present nute wise in the coco.
I've played with the light distance a lot and think I've found the sweet spot with distance and dimming but ill keep an eye on that too.

what other info would help diagnosing, sorry I'm just still learning the ways

 

[phxazcraig]

They don't look too bad to me, though I suspect a bit overwatered. Possibly a bit underfertilized too, but at this stage it's so easy to burn them that I prefer a slower start without burn.

When I transplant Jiffy pots with new seedlings into bigger pots, there is a delay in growth while the plant recovers and builds up a root structure. It can seem like things are stalled, but I think they are accelerating with the bulk of the changes happening underground. Be sure not to overwater those pots so the roots can get down to the bottom without hitting a layer of water.

You might try some initial fertilization at a very low level. Find a chart for your soil type, select seedling, and dilute anywhere from 50% to 90%.

In my experience, at this stage we tend to overdo everything. Overwater, overfertilize and overlight. With a 600w LED, you can burn seedlings to a crisp in no time. How much PAR/PPFD are you putting on those lights? You do the math and estimate PAR for us based on the light chart. Distance from plants is meaningless. You need a measurement, especially if a dimmer is involved.

Your soil - that hay (?) you have spread on top makes me nervous. I can't see any good coming from that, but it looks like a great place to raise bugs.

 

[mysticepipedon]

Your soil - that hay (?) you have spread on top makes me nervous. I can't see any good coming from that, but it looks like a great place to raise bugs.

Agreed. Get that crap off.

 

[BorealCuring]

Keep in mind that root development takes priority in the beginning. So while you may not see much happening up top, as long as you're not drowning the roots, there's a lot going on below. Keep this process in mind: Build roots -> Growth spurt. Build roots -> Growth spurt. At one point, you'll have enough roots to really speed growth. You'll notice it most once you transplant and they take off. Apart from harvest, that initial explosion after the first transplant is my favorite time.

 

[remdog]

They don't look too bad to me, though I suspect a bit overwatered. Possibly a bit underfertilized too, but at this stage it's so easy to burn them that I prefer a slower start without burn.

When I transplant Jiffy pots with new seedlings into bigger pots, there is a delay in growth while the plant recovers and builds up a root structure. It can seem like things are stalled, but I think they are accelerating with the bulk of the changes happening underground. Be sure not to overwater those pots so the roots can get down to the bottom without hitting a layer of water.

You might try some initial fertilization at a very low level. Find a chart for your soil type, select seedling, and dilute anywhere from 50% to 90%.

In my experience, at this stage we tend to overdo everything. Overwater, overfertilize and overlight. With a 600w LED, you can burn seedlings to a crisp in no time. How much PAR/PPFD are you putting on those lights? You do the math and estimate PAR for us based on the light chart. Distance from plants is meaningless. You need a measurement, especially if a dimmer is involved.

Your soil - that hay (?) you have spread on top makes me nervous. I can't see any good coming from that, but it looks like a great place to raise bugs.

Yeah I'm leaning towards overwatering, as u say its easy to get carried away and I might have overdone it. Especially since I haven't actually transplanted at all, just started it in the final 5 gallon pot. But I'm wondering although its a big pot is it normal for it to be slowed this much, I mean it did sprout on the 12th and from what I understand autos switch to flowering themselves and sort of live 60 to 90 days. Should my plant not be a lot larger for 3 and a half weeks since sprouting, seems off to me growth wise. That's what I was also concerned about, nutrient issues since the leaves are yellowing slightly but think this is normal when using organics.

For light levels I don't have a lux meter yet but did a bit of maths based off PPFD maps for my light and distances and I'm pretty certain my Daily Light Integral is somewhere between 25 to 35 which seems maybe a little high for the stage I'm at. Thing is I did a lot of looking into light distance, trying to find the sweet spot to prevent stretch yet not to burn the plant of course.

I'm not using traditional salt fertilisers but instead went for the living soil (coco?) route which involves creating a microbiome in the medium similar to what would be found in natural soils outdoors, this means less feeding in veg and requires an occasional top dress or compost tea to provide for the microbes which feed the plant. Because there's supposedly a bunch of beneficial living stuff in there the medium has to be kept at least slightly moist, from what I've read always between a 3 and 7 on a scale from bone dry to sopping wet. This is why I've added the barley to the top because it slows down evaporation of the water from the medium, ofc I'm pretty inexperienced so just following what others have done.