Can only speak from personal experience but discoloration from cold, for me at least, started when temps dropped below 10C with a clear purple starting at the flowers themselves, looking like this:


I had some outsiders that did not root well and didnt really get a lot of nutes to begin with, followed by budrot. They looked like this:


I'd check nutes and the way you water.

Are you suggesting this might be the start of bud rot? My last grow had a very distinctive smell when it developed, but this doesn’t. I’ve inspected the buds and I don’t see any signs of mold

Part of it must be genetics, I dont know about the spots but the rest looks pretty standar for when I grow a strain that migh show blue. That mixes sometimes with the fade and creates a copper color. This grow Im finishing they've been under 5ºC for many days when the lights were off without a problem, and only one of them showed blue, I was hoping for more...

Whatever the spots are, its probably nutrient related, I see a lot of crispy tips. I dont think theres anything to worry about though. Could also be the light too close if the crispy tips are only on the tops.

DURBANPOISON.AAA said:

My second grow:

Photoperiod feminized plants in coco/perlite, I am supposed to be about 2–3 weeks from harvest, but ive been dealing with an unresolved issue for 2–3 weeks. I suspected pH issues, then cold stress caused by running an AC and dehumidifier 24/7 to keep humidity at 40–50% in a very humid environment. Temperatures dropped to around 16°C, later adjusted to 19–22°C, but growth is still slow and leaves are showing discoloration and drying.

I lost my previous grow lost to bud rot & would really appreciate some advice to prevent losing this one as well.

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Thats looking good in there, you're getting close to the finish! Some strains take on "fall colors" in their fan leaves as the plant is winding down. Probably not 100% accurate but the plants have what's called anthocyanins, some a lot more than others and you see it in the slight blush appearance in stems sometimes. So their production is kicked in when temps get lower, I grow outdoors and the turning point seems to be about 60° and lower. Then on top of that, the plants stop giving energy to the fan leaves and they focus more on the flowers, so the plants begin to take on a natural fade.

A natural fade starts at the lowest leaves and works it's way up, usually two nodes shifting at a time upward and it's a slow process, thats how you distinguish a fade from a deficiency. Color wise, they will lose chlorophyll so they may appear lighter or yellower, but leaves with the anthocyanins won't look it became they're holding that color instead of the green.

All this to reel you it looks good in there, the color shift has nothing to do with bud rot and while it is a deficiency of sports , it's not the kind you want to try and correct.

I do want to mention something though... that leaf you're holding with the red edges and I want to try and interpret it for you. The blotchy discoloration is likely normal, that is something I've seen when there was a sudden onset of cold and the anthocyanins dont fill in the color evenly... maybe there wasn't a uniform leaf temperature??? Anyways, that to me looks normal. But it also has a burnt edges appearance, and that's usually a sign that it got a hot dose of nitrogen at a level it shouldn't have gotten and at a time it shouldn't have gotten it. This can also trigger your leaves that changed color from anthocyanins to look exceptionally dark, even black but genetics are in play too. So I'm thinking maybe you slipped some nitrogen in there and it wasn't a bad call entirely... it wasn't toxic levels and it has held on to color for the finish, and doesn't look like it affected bud development.

So for your next run, I would say do exactly what you did this run, but when you do that N supplemental feed, maybe just back off the dose a smidge. You'll wind up with more yellow at the finish but it will be natural.

Edit: Sounds like you noticed it's not stinking up like you think it should. That also tracks with excess nitrogen.

Cold, unless well below freezing won't effect a plant like that. It will slow down growth and cause the green chlorophyll to break down allowing anthocyanins within to show purples and reds.

So unless your plant has been exposed to 30F or less for several hours or more there's something else causing the leaves to dry out. It could be pH, light burn or any number of issues.

PlumberSoCal2 said:

Cold, unless well below freezing won't effect a plant like that. It will slow down growth and cause the green chlorophyll to break down allowing anthocyanins within to show purples and reds.

So unless your plant has been exposed to 30F or less for several hours or more there's something else causing the leaves to dry out. It could be pH, light burn or any number of issues.

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Rarely just one thing is it? Usually one issue with two others aggregating it

Wish I'd taken pics of a Durban I had dumped a bunch of N on about 3 weeks from harvest. Plant went extra purple in the cold (yes a Durban) and fan tips took on the very distinctive behavior of corkscrewing and drying out. Kind of like how that one looks. They curve and die, they curl and die, but when they corkscrew and die I think that is a very particular symptom. It can be a couple things like environment and pH, but everything else I'm seeing points to N.

I was edging towards either natural fade or a root issue. If you use soil you can actually check by gently sliding her out the pot to check the roots right before watering. Should be bright white. Other than that there's nothing you can do without hurting your harvest at this point. Just trim off dead leaves and keep on going. Almost there.

Ah and i wasnt suggesting you'd get bud rot, that was just my own luck as they were outside and the chances then are very high when there's whatever problem popping up.

I was about 4 days days away from harvest & noticed this. This is so disappointing. This now the my second grow that I would have to thrash.

Lost my first ever grow to budrot & now it seems like I am about to loose the second

DURBANPOISON.AAA said:

I was about 4 days days away from harvest & noticed this. This is so disappointing. This now the my second grow that I would have to thrash.

Lost my first ever grow to budrot & now it seems like I am about to loose the second

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Ive had that happen 3 times now , it sucks especially just before harvest...i would still keep any bud you can salvage though, i'm smoking stuff i had to chop early and its ok for a daytime smoke.
i think what happened with mine (in coco) was i didnt flush enough through the grow so salts built up in the pot, which you dont notice while its growing, then at the end i added extra PK14/15 and it just tipped it over and locked up...I also let one dry out which messed everything up...plus mine were autos which made it worse....i then switched to a photoperiod in soil and its been completely different , i havent had one issue so far...

I’m currently growing in coco/perlite, so I’m struggling to understand how this could be bud rot. My humidity during flower has consistently been between 40–50%, and while temperatures did drop to around 16°C at times, they never exceeded 24°C. I’m also running two oscillating fans,one at the bottom and one at the top so airflow is good. I definitely didn’t overwater this time, as I was extra careful after overwatering on my last grow.


I’m also not getting that distinctive smell I experienced during the previous grow when I did have bud rot, and I don’t see the dark brown spots I saw then either. These discolourations are more on the yellow side.

DURBANPOISON.AAA said:

My second grow:

Photoperiod feminized plants in coco/perlite, I am supposed to be about 2–3 weeks from harvest, but ive been dealing with an unresolved issue for 2–3 weeks. I suspected pH issues, then cold stress caused by running an AC and dehumidifier 24/7 to keep humidity at 40–50% in a very humid environment. Temperatures dropped to around 16°C, later adjusted to 19–22°C, but growth is still slow and leaves are showing discoloration and drying.

I lost my previous grow lost to bud rot & would really appreciate some advice to prevent losing this one as well.

Click to expand...

I’m not seeing bud rot. I think it’s just the plant’s senescence showing as you are getting close to harvest. I’m guessing the unresolved ph issue likely caused lockout early on and shut your plant down. now you are nearing harvest so the growth is pretty much done, could see some buds fill out a little more before then.

I don't see that you mentioned what/how much you're feeding. I don't think its bud rot either, but only you can confirm that by examining the buds.

DURBANPOISON.AAA said:

I’m currently growing in coco/perlite, so I’m struggling to understand how this could be bud rot. My humidity during flower has consistently been between 40–50%, and while temperatures did drop to around 16°C at times, they never exceeded 24°C. I’m also running two oscillating fans,one at the bottom and one at the top so airflow is good. I definitely didn’t overwater this time, as I was extra careful after overwatering on my last grow.


I’m also not getting that distinctive smell I experienced during the previous grow when I did have bud rot, and I don’t see the dark brown spots I saw then either. These discolourations are more on the yellow side.

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Coco you say? How many fertigations a day? With what nute line and strength?

If you're trying to water like it's in soil that could be the problem

I have been feeding 3 part liquid nutes which I stopped about 2/3 weeks ago & began to flush. Any suggestions? Should I perhaps just chop them up & begin the drying process?

It is hard to see in the pics but will try to take a few more

PlumberSoCal2 said:

Coco you say? How many fertigations a day? With what nute line and strength?

If you're trying to water like it's in soil that could be the problem

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I water just once a day as soon as it is lights on & followed the directions on the bottle of my nutes. I did go a bit hard on the nutes a few times but when I noticed the tips were getting burnt I went back to the directions on the bottle

Hope this helps

DURBANPOISON.AAA said:

I have been feeding 3 part liquid nutes which I stopped about 2/3 weeks ago & began to flush. Any suggestions? Should I perhaps just chop them up & begin the drying process?

It is hard to see in the pics but will try to take a few more

Click to expand...

Never flush and never give a plant in coco just water, even if it's been pH'ed.

3 fertigations per day minimum with 10-20% runoff each and every time.

Jist water as needed to keep coco wet first week. Start after 1 week with a 25% nute water mix. Up to half strength after 2-3 weeks and full strength nutes at 1+ month. Lower calcium 4 weeks into flip and keep the 3 a day going until harvest.

While some are promoting once a day fertigation in coco you can't argue with the results I've achieved

In the past 2 years I've grown a couple dozen trees in 3-4 gallon pots of coco. I no longer add perlite.

Fertigate your plant(s) minimum 3 x's a day with 10-20% runoff. 5 x's a day is even better