Grow deux - Critical Kush in rural Thailand

[IsanFarmer]

Does anyone have any advice with my questions in post #98 Re Dutch Pro nutrients and their unorthodox advice about the point at which you should measure the EC when mixing nutrients? It would be much appreciated!

 

[Trash_2002]

Does anyone have any advice with my questions in post #98 Re Dutch Pro nutrients and their unorthodox advice about the point at which you should measure the EC when mixing nutrients? It would be much appreciated!

i think they instruct this way because the additives doesn't have a lot of nutritional value like the base nutrients, and +0.07 of explode isn't high, i would measure after everything added tho, but i don't think measuring like they say is a problem, all good too.

 

[IsanFarmer]

i think they instruct this way because the additives doesn't have a lot of nutritional value like the base nutrients, and +0.07 of explode isn't high, i would measure after everything added tho, but i don't think measuring like they say is a problem, all good too.

Sometimes I have to add a "Multi Total" supplement as well which would increase the EC further, I think from now on I will measure the EC after I have added everything. When I water my plants I take them out of the tent to make it easier but during this time (about an hour) they're not under the light. Does this matter?

 

[IsanFarmer]

Day 66

Three of my plants don't look like they're very well. They have brown patches on some of their fan leaves and the tips are curling. The plant with the worst symptoms also has a purple stem. My diagnosis is a potassium deficiency but symptoms for potassium excess are also similar so I'm not sure if it's deficiency or excess? Or am I completely wrong and it's something else? The last feed was 1.27 EC. Can anyone shed any light on this?

I've also read that the purple stems can be caused by low temperatures. The temperature in my grow room is ~76 to 80 during the light cycle and ~72 to 75 when it's dark. Is 72 too low?

The plants are getting 480 to 675 PPFD but maybe that's a little too high? Does anyone have any experience of the Critical Kush strain and know the optimum PPFD for the later stages of flower?

 

[IsanFarmer]

After apeaking with @benjones I think there is a good chance that this has been caused by letting the soil dry out too much in between watering/feeding, which has caused a build up of salts in the soil and raised the EC significantly. So the problem is actually a nutrient excess.

I've started watering more frequently but the damage is already done. Maybe I should flush the soil before the next feed? What do you think @Trash?

 

[Trash_2002]

After apeaking with @benjones I think there is a good chance that this has been caused by letting the soil dry out too much in between watering/feeding, which has caused a build up of salts in the soil and raised the EC significantly. So the problem is actually a nutrient excess.

I've started watering more frequently but the damage is already done. Maybe I should flush the soil before the next feed? What do you think @Trash?

i agree with @benjones.
i woudn't necessarily flush, i would just water more frequently with more runoff.
That brown spots looks more like a Phosphorous lockout than Potassium deficiency tho.
maybe the media PH is too acid with the extreme dry out, watering more frequently with more run off should help in all fronts.
cheers!