Old leaves yellowing and dying

4th week into flowering. Little over a week ago the fan leaves started yellowing. Now they are drying out and dying. The leaves on the side branches have yet to be affected. It's only problematic on lower to mid fan leaves off the main stalk. Could someone please fill me in on what this looks like?

Box is steady mid 70's under 400w HPS a little over a foot above the tops. Plenty of ventilation and air ciruclation. Less than 40% humidity.

3 plants. Using bat guano of unknown NPK mixed in soil every other week. 40ml fish emulsion (2%-5%-.2%) with water every 5th day. 1-2Tbs cane sugar 2x week. Used blood meal (12-0-0) during veg. Laid off on that once flowering. MG organic soil.

Any help would be appreciated. Let me know if any more info is needed.

Thanks!

The rule of thumb with old fan leaves dying is an N def. Old fan leaves are fine, but how far up the plant is it creeping? Here is some info: "Towards the middle to end of flowering stages, the plant will show a nitrogen deficiency almost always. This process is completely normal and just let the plant naturally yellow out as it uses it's stored nutrients. This actually helps you by getting ready for final flushing and then harvesting. At this point DO NOT not use nitrogen to fix the problem. The yellowing leaves will then eventually drop off after the plant is done with them." International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!

Picasso345 said:

The rule of thumb with old fan leaves dying is an N def. Old fan leaves are fine, but how far up the plant is it creeping? Here is some info: "Towards the middle to end of flowering stages, the plant will show a nitrogen deficiency almost always. This process is completely normal and just let the plant naturally yellow out as it uses it's stored nutrients. This actually helps you by getting ready for final flushing and then harvesting. At this point DO NOT not use nitrogen to fix the problem. The yellowing leaves will then eventually drop off after the plant is done with them." International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!

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Thanks for the reply Picasso345.

I looked a little closer and the leaves are pretty yellow from the bottom to the middle, then getting lighter green at the top. Looks like they are on their way to yellow. And again it's only off the main stalk, no side branches are affected.

Flowers look really nice and healthy.

I read that link you posted earlier today and was in the air over N deficiency or heat stress. Will I be okay without adding more N or should I give it a final low dose to keep these big leaves from falling off? Will this affect the flowering in a negative way if I do nothing to correct this?

i'd say (i'm no pro by any means) that that plant looks too early in flowering / buds not developed enough for that kind of yellowing to be taking place all over the place.

picasso's quote is definitely a good point but i think it's referring to more of the yellowing at the end of the flowering when the buds are taking up all the rest of the nutrients in the plant...thus yellowing the leaves.

i'd say give them some kind of N boost in nutes, it's too early to be thinking about flushing or any of that yet. pull off the deadest yellow leaves as the plant is just going to try and fix them and less energy will go to the buds...but the somewhat green / yellow leaves will hopefully turn back around.

hope this helps.

I'm going to agree with roughnice and say you should try and give them just a little N. If your temps are in the 70's that is so perfect that I don't think heat stress is a worry.

roughnice said:

i'd say (i'm no pro by any means) that that plant looks too early in flowering / buds not developed enough for that kind of yellowing to be taking place all over the place.

picasso's quote is definitely a good point but i think it's referring to more of the yellowing at the end of the flowering when the buds are taking up all the rest of the nutrients in the plant...thus yellowing the leaves.

i'd say give them some kind of N boost in nutes, it's too early to be thinking about flushing or any of that yet. pull off the deadest yellow leaves as the plant is just going to try and fix them and less energy will go to the buds...but the somewhat green / yellow leaves will hopefully turn back around.

hope this helps.

Click to expand...

Picasso345 said:

I'm going to agree with roughnice and say you should try and give them just a little N. If your temps are in the 70's that is so perfect that I don't think heat stress is a worry.

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Thanks for the help guys. Will give a blood meal N boost at the next watering. Hopefully things will pick up.

Good luck.