Stunted growth, small & bright green leaves

Hi all,

The plant is a Jack Herer autoflower.

• 4 weeks since sprouting, 1 week into flower.
  
• Soil - BioBizz Light Mix
• Smart/fabric pot 3.8l(0.83 gal)
• Homemade LED lights (120W), 20cm(7.8 inches) from the plant top. Very little heat above the plant.
• Light schedule 24/0
• Temps always around 25°C (77°F)
• Air circulation is more than adequate

The problems started a little over a week ago. As you can see in the photos the leaves are pointing down, the color is not right and in the past week I have barely seen any progress in overall growth.

I lightly fed the plant twice with some cal/mag (has some nitrogen in it) and some organic bloom (2-7-4). I repeat, lightly. When I realized something was wrong I flushed the plant about 3 days ago and tried to lower the pH of the soil but with no success. The soil pH stubbornly remains at 7.

To me this looks like over watered and root bound plant but I find that hard to believe since it's grown in a fabric pot. (I chose a small pot because this is a 30x30cm or 11x11 inches grow space). I also suspect that the amount of light the plant gets is just too much, but then the problems would have been there from the start.

I water the plant when the pot is light (2-3 days) with 1.5l(0.4 gal) water pH at 6. I remove 95% of the runoff water. Now I lifted the pot from the ground so it dries faster.

I had the same problems in my previous grow but then I used the regular pot and transplanted in the fabric one and I didn't have the soil pH meter so who knows what the problems were then.

If you have any suggestions please do help Take care!

Have you left that ph meter in there? Because you're not supposed to, leads to inaccurate readings. Ph is also not very useful when you're growing in soil. It varies too much depending on where you are in the medium, and there's almost always a part of the root zone that's at the perfect ph for each nutrient.
What's your watering schedule like? Do you use the weight method?

edit: she looks hungry for nitrogen and slightly underwatered to me

Your light is far far too close.

CanadianJim said:

Have you left that ph meter in there? Because you're not supposed to, leads to inaccurate readings. Ph is also not very useful when you're growing in soil. It varies too much depending on where you are in the medium, and there's almost always a part of the root zone that's at the perfect ph for each nutrient.
What's your watering schedule like? Do you use the weight method?

edit: she looks hungry for nitrogen and slightly underwatered to me

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I wrote about my watering schedule and no, I don't leave the pH meter in the soil.

hotrodharley said:

Your light is far far too close.

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It is close, but no heat above the plant what so ever. Isn't that usually the issue when it comes to lightning?

mj92 said:

I wrote about my watering schedule and no, I don't leave the pH meter in the soil.

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Right, sorry. Been having a shitty day so far and read it too fast.
Rest of my post stands though.

mj92 said:

It is close, but no heat above the plant what so ever. Isn't that usually the issue when it comes to lightning?

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LEDs have been known to bleach upper foliage when they're too close, and light that's too intense causes stress.

mj92 said:

It is close, but no heat above the plant what so ever. Isn't that usually the issue when it comes to lightning?

Click to expand...

It’s not just heat. In fact it’s not a heat issue. Most manufacturers suggest starting at least at 22”-24”. Most instructions with the lights will have suggested distances.

Grow Light Closest ~ Sunlight - Furthest
150W 8″ (20cm) 10″ (25cm) 12″ (30cm)
250W 10″ (25cm) 12″ (30cm) 14″ (35cm)
400W 12″ (30cm) 14″ (35cm) 19″ (48cm)
600W 14″ (35cm) 16″ (41cm) 25″ (64cm)
1000W 16″ (41cm) 22″ (55cm) 31″ (79cm)

https://www.growweedeasy.com/how-far-grow-lights

I'm pretty sure you locked out Zn with the double dose of calmag and bloom.

Any pics of say, a week ago, before the damage? Also what nutrients you are using so I can check the labels.

Also humidity. Didn't see that there. 77 is a little cool for LEDs and soil, in my opinion.

Here's where you see it best. The top I circled has every sign. Very light green, dry and curled foliage, and those brown tips.

Do a @hotrodharley and stab the shit outta your medium (not too much) with BBQ skewer - helps get oxygen and water to the root zone.

It does look like a zinc issue to me.

Fabrics don’t get rootbound but they can still run out of space.

A good root/soil ratio is important otherwise you’re gonna have a nightmare locking stuff out.

I dare say when you water it’s running through channels and not soaking the medium leading to dry spots.

If I were u I’d stab the medium give it a good watering then a balanced all round feed the leave it for a few days see how she goes.

There're over watered due to your flush.
Let the medium dry out, and all should be good.
Also, Calmag once a month, no more, if ever in soil
Only in hydro for Calmag really that's where it is needed