Tips of buds continue growing for some reason.

[Ibechillin]

It’s not foxtails

It’s senescence

Supporting research/experience/evidence to support this would be great.

 

[shaggyballs]

I suspect it may be hormones in one of the additives for late flower.
This can make some cultivars start second stage growth, sometimes getting a bit fluffy in the process.
What are the late flower additives used?

 

[caliprop215]

It looks like the tops want to revenge but flowering just a little. That's odd.

 

[FarmerWilly]

About the Ir settings you want to use the high setting on the tops of leaves:

"Not all materials emit the same amount of infrared energy when they are at the same temperature. In general, most materials emit more infrared energy than shiny metals do - they have higher "emissivity." (Emissivity is expressed as a number between 0 and 1, with 0 being non-emissive and 1 being perfectly emissive). Reflective surfaces are less emissive than dull surfaces. Weathered or oxidized metals are more emissive than polished, shiny metals.

If you need to take temperature readings on low emissivity objects regularly, consider an IR thermometer that enables you to compensate for variations in emissivity. For example, the Fluke 561 Infrared Thermometer enables you to set emissivity to "High" (for measuring most surfaces, such as wood, paint, rubber, plaster, or concrete), "Medium" (for oxidized metals or granite, for example), or "Low" (for shiny metals)."

How about your lights on and lights off temp difference? That could cause stretching if it varies a decent amount.

Thank you very much for this info.

Lights on and lights off difference is quite a bit. Day is around 30c and night is around 20c.

 

[FarmerWilly]

I run a sealed room with CO2, AC & DeHuey..

I only get foxtailing if my temps are too high or the plants have too much food.

In my experience, most plants I work with prefer a canopy temp of less than 80 degrees in flower. Typically I shoot for 78-80 in early flower (weeks 1-4), and then dial down to 74-78 in late flower (weeks 5-10)..

I also cut down CO2 to 300-500ppm the last two weeks.

I use the plants as a guide and let them tell me what they like.

Best of luck with future endeavors!

Interesting. These temps you meantion seem a bit low for me to get much benefit from co2. 78-80f is like 26c. But what if you would increase RH? They would handle higher temps better then

 

[Ibechillin]

Lights on and lights off difference is quite a bit. Day is around 30c and night is around 20c.

Found the problem! You just need to increase your lights off temperature, large differences will cause stretching. Ideally you want less than a 10F degree day night difference for tight dense growth. 30C (86F) day to 20C (68F) night is an 18F degree difference, aim for around 26C (78.8F) night temps.

 

[FarmerWilly]

Heat from the lights.

I don't think it's understood why this happens. However, if energy from the lamp heats the plant, the plant gives off more energy in the form of heat. Literally, energy that should of helped grow the plant, is leaving again. So we have a higher proportion of far/infra red around the buds. Which is a shade response trigger.

I am totally making this up as I go. Except the bit about it being heat from the lamps. I have seen it many times, looking just like that.

The signs of high feed arn't there.

I believe you're right. Radiant heat from lights. I'll raise them up. I would just need to remove those easyrolls. I don't know how those plants got so big. I vegged for 2 weeks, but they were very well rooted clones too. Plants are like 5 feet tall (around 150cm).

 

[FarmerWilly]

The pictures seem to show healthy growth with only the tallest nugs on the plant exhibiting the stretching, its gotta be heat/IR at top canopy level. If you cant raise your lights any higher, you could use the height at which the plants begin to foxtail as your known max plant height to work with and adjust veg time and strain stretch/plant numbers accordingly.

Yup, I'll try 1 week vegging next time and after that maybe even straight to 12/12 from well rooted clones as they will be still vegging in 12/12 for first 2-3 weeks.

 

[FarmerWilly]

I suspect it may be hormones in one of the additives for late flower.
This can make some cultivars start second stage growth, sometimes getting a bit fluffy in the process.
What are the late flower additives used?

I'm using Canna PK 13/14 at 5th and 6th week. (I'm all Canna)

 

[FarmerWilly]

Found the problem! You just need to increase your lights off temperature, large differences will cause stretching.

I know, but I didn't know the streching will go on this far in flowering. I was thinking it's more for first 3 weeks to keep in mind.

 

[Ibechillin]

Plants just react to the environment, stage of life doesnt matter they react the same (re veg after harvest is a great example). Only a few causes of stretching and in this case its a combination of large day night temp swings during early flower causing excessive stretch, which put the top colas too close to the lights causing more stretching at cola tops. With better controlled night temps on the next cycle you could probably still do a 2 week veg since the plants shouldn't stretch as much.

 

[PuKKiE]

Hi Willy,
Just wonder what water are you using to get that ppm on the nutes. I used tap water and if I follow the dosage from Canna, the PPM is always higher that what supposed to be.