Nute burn in organic soil

[marijuaman]

Hey all! These plants are 47 days old and suffering from what I think is nute burn. Medium is OF/perlite, with just plain PH 6.3-6.5 tap water apart from a single top dressing. I had some low soil PH issues in the first 3 weeks, so I decided to top dress with build-a-flower around week 3 in attempt to balance PH and give a pre-flower boost. I think this made the soil too hot and what started with burnt tips is slowly progressing. Do you think the plants will ride it out if I keep going with plain water, or do I need to take measures to remedy the issue?

 

[Bruce Campbell]

Have you used any other feed besides the build-a-flower top dress?

Have you been watering to run-off?

OF has very little K. Not sure how much potassium build-a-flower provides, but googling some of the ingredients made it seem like it may not have much. And, the progression looks typical of potassium deficiency - especially the necrosis at the saw tooths.

OF has a decent amount of calcium, and build-a-flower also looks like it has some. And, your tap water may also have some (but the low-ish pH makes me think it has less than mine). High Ca can reduce K uptake, which may be making things worse if there was low K to begin with.

I'd look for a synthetic fert that has high K and low Ca. I use the cultivation nation trio, and the grow formula is 2-1-6 with no Ca.

 

[CannabisMingus]

I suggest posting this in the infirmary.

 

[marijuaman]

Have you used any other feed besides the build-a-flower top dress?

Have you been watering to run-off?

OF has very little K. Not sure how much potassium build-a-flower provides, but googling some of the ingredients made it seem like it may not have much. And, the progression looks typical of potassium deficiency - especially the necrosis at the saw tooths.

OF has a decent amount of calcium, and build-a-flower also looks like it has some. And, your tap water may also have some (but the low-ish pH makes me think it has less than mine). High Ca can reduce K uptake, which may be making things worse if there was low K to begin with.

I'd look for a synthetic fert that has high K and low Ca. I use the cultivation nation trio, and the grow formula is 2-1-6 with no Ca.

This could be the issue. Would Mega Crop at 9-6-17 NPK work?