Can anyone identify this issue?

Hey there,

I'm growing two different types of plant just now in the same (small) tent. One is showing the issue in the picture below and the other looks completely fine. They are both 8 weeks old from germination. Can anyone tell me what the issue likely is? I thought originally it was a calcium / magnesium issue but tried adjusting for that and it's not made any difference (better or worse). Looks to affect around 10% of the leaves.

Any ideas? Thanks!

EDIT: From the sticky on this forum category, I'd guess potassium deficiency? Can anyone confirm?

Over feeding. Extreme tip burn spreading to the leaf margins

Try feeding at ⅔ what you were not adding more

What's your medium, nutrient line, and how often do you feed? How much of recommended dose do you use?

I'm using bio-bizz all-mix and bio-grow and bio-bloom. Never used any nutes in the first few weeks of veg stage. Now, I'm using as the schedule shows - 1ml of bio grow per ltr and 2ml of bio bloom per ltr. Feeding about 2 ltr per plant every couple of days (when they are both dry and light in weight)

EDIT: Should also mention that I think I've been underfeeding the bio-bloom which is the nute that has potassium. At week 8, this should be three times as much according to the schedule. Hence why I thought it may be potassium.

did you flip to 12/12 yet?
what size container are they in?
please provide full plant picture.
what light are you using?
are you feeding anything else besides bloom and grow?
what are temps and RH like?
do you water before they wilt to show they are thirsty?

JMystery said:

I'm using bio-bizz all-mix and bio-grow and bio-bloom. Never used any nutes in the first few weeks of veg stage. Now, I'm using as the schedule shows - 1ml of bio grow per ltr and 2ml of bio bloom per ltr. Feeding about 2 ltr per plant every couple of days (when they are both dry and light in weight)

EDIT: Should also mention that I think I've been underfeeding the bio-bloom which is the nute that has potassium. At week 8, this should be three times as much according to the schedule. Hence why I thought it may be potassium.

Click to expand...

Burnt leaves and K deficiency do often look similar, but from your description, it seems very unlikely you've been overfeeding
The leaf in the picture is a textbook image of a potassium deficiency.

Thanks guys - appreciate the input as always!

ALPHA.GanjaGuy said:

did you flip to 12/12 yet?
what size container are they in?
please provide full plant picture.
what light are you using?
are you feeding anything else besides bloom and grow?
what are temps and RH like?
do you water before they wilt to show they are thirsty?

Click to expand...

They are both autos. I'm using a Spiderfarm SF1000 on 24/7 in a pretty small tent (80 x 80 x 120). They are both in 9L Airpots and drainage obviously is good. Not feeding anything except bio grow / bloom for now (except some calmag over the last couple of feeds - now stopped this). Will be adding top max later. Temps are pretty reasonable - not sure exactly but marginally over room temperature. I'm watering them every 2 days simply because lifting the pots feels light. These are probably my 11th / 12th plants so I got good at judging when to feed them.

Billy the Mountain said:

Burnt leaves and K deficiency do often look similar, but from your description, it seems very unlikely you've been overfeeding
The leaf in the picture is a textbook image of a potassium deficiency.

Click to expand...

This is what I'm thinking given my discovery today that I've been underfeeding with bio bloom (which is potassium high). Next feed I'll start them on correct amount and see if there's an improvement. Super angry at myself for missing this - but it's been a year or so since my last grow. Kinda forgot some stuff.

Thats a potassium deficiency 100%, advanced potassium deficiency. Stick to a 1 part balanced feed and drop the 74 part separate feed and you wont have these issues. Cannabis needs a balanced feed from beginning to end.

Cpappa27 said:

Thats a potassium deficiency 100%, advanced potassium deficiency. Stick to a 1 part balanced feed and drop the 74 part separate feed and you wont have these issues. Cannabis needs a balanced feed from beginning to end.

Click to expand...

I've always used the Bio-bizz products - can you recommend a one-part feed that I can use going forward? Would make my life easier too in fairness.

JMystery said:

I've always used the Bio-bizz products - can you recommend a one-part feed that I can use going forward? Would make my life easier too in fairness.

Click to expand...

Here is a simple and very effective fertilizer yo use from beginning to end



Here is one that is organic beginning to end

Thank you for the response - I'll sort that for next time!

JMystery said:

Thank you for the response - I'll sort that for next time!

Click to expand...

No problem you could even just go get some miracle grow now and start using it, its sold everywhere.