Leaf Tips And Edges Turned Black

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BCSparky

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I'm growing a plant outdoors in BC, Canada, and about a week or 2 ago I noticed the edges and tips of some of my leaves were turning black/grey. The tips are also clawing or curved up.

The strain is Euphoria from Royal Queen Seeds. Night time temperature around here goes about as low as 12 degrees C. I did give it some doses of compost tea right before the symptoms appeared. I suspect that the problem is caused by fish fertilizer that went bad, or calcium toxicity or magnesium toxicity.

I also pruned quite a few branches in week 3 of flowering (not long before the symptoms appeared) and maybe the plant was less insulated from the cold, causing those symptoms.

Tell me what you think.
Leaf tips and edges turned black
 
rootexcess

rootexcess

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I looked at the photo prior to reading your post and I immediately considered it to be temp related, then I read your post and based on the temp you provided I would credit it to that.
 
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BCSparky

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Damn. That's probably what it is then. I noticed that it was happening to all the outer leaves which were exposed to the most cold. I think she would be doing ok, but I pruned away her shaggy coat, and all the cold got right in there...

Maybe i'll bring my little 750 watt heater again. Do you think it would do her any good to heat the roots with a fan heater?
 
rootexcess

rootexcess

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Damn. That's probably what it is then. I noticed that it was happening to all the outer leaves which were exposed to the most cold. I think she would be doing ok, but I pruned away her shaggy coat, and all the cold got right in there...

Maybe i'll bring my little 750 watt heater again. Do you think it would do her any good to heat the roots with a fan heater?

It's really hard to say man, it may help as long as it's not going to cook her or cause one area to be hot and the other area of the plant to still be cold.
 
Daikokuten

Daikokuten

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Damn. That's probably what it is then. I noticed that it was happening to all the outer leaves which were exposed to the most cold. I think she would be doing ok, but I pruned away her shaggy coat, and all the cold got right in there...

Maybe i'll bring my little 750 watt heater again. Do you think it would do her any good to heat the roots with a fan heater?
The color doesn't equal damage. That said, 12c is a bit uncomfortable for cannabis and could slow growth. Purpling by temperature is plant specific but mostly occurs around 65c and below. I have gone to 55 and saw slowed growth in most strains, saw purpling in some plants that didn't purple at 60, my usual target temperature. A small heater may be worthwhile or not. I assume you don't know this cut intimately so i would look at getting a heater in there. That all said there were no physical symptoms noticeable and the root balls weren't any lower temperature wise than they get at 60(root ball normally stays 10 above, at 60 mine are usually 71-73). The color is simply anthocyanins being produced in response to the cold air temperature. It is not indicative of damage and doesn't negatively impact photosynthesis or growth. It does replace the yellow you would normally see below the green though so it could hide hunger and chlorosis. It is not indicative of ph problems or lockout or nutrient issues. Lastly, typical ceramic and other heaters dry the air a lot. Humidity can become an issue if you don't have a lot of plants or a humidifier to maintain it. Further to that though ive never seen a problem so long as humidity is at least 30ish. Might not be ideal but wouldn't be a pressing issue and wouldn't slow growth like the cold would.
 
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BCSparky

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I think there is also chlorosis going on. I took another pic just now. Some of the leaves have filled and the spread of symptoms has slowed since they began.
Euphoria Symptomz
 
Greatlakes

Greatlakes

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I live in northern wi. Every yr my plants freeze several times before I take them down. Never a hard frost but they have got down to 28.
When the sun comes up they bunce right back.
secret is to water the shit out of them before it gets cold. It insulates the roots.

P.s. This is another reason that using a lot of compost in your soil is wise especially in colder areas. As the compost continues to break down it creates heat...keeping your roots nice and toasty during the long cold nights.
 
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BCSparky

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Thanks for the tips. I was under the impression that water would make the effects of cold worse. I guess I'll just let my plant weather it out. I put the heater oscillating back and forth on the leaves for a little boost. I noticed that the main cola seemed to have actually sped up growth over night.
 
Greatlakes

Greatlakes

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Thanks for the tips. I was under the impression that water would make the effects of cold worse. I guess I'll just let my plant weather it out. I put the heater oscillating back and forth on the leaves for a little boost. I noticed that the main cola seemed to have actually sped up growth over night.
No...just the opposite. It works like a geothermal heat.
 
Madmax

Madmax

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Its not coldness related..i never get that and my temps are 5 deg over night.uno frost never kills plants,its the quik thaw that buggers them..
 
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BCSparky

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Yeah... it doesn't really look like purpling so much as burned leaf. the texture is kinda bumpy and charred looking. I could see the leaf tips curling up from the cold, but the color is probably due to some nutrient problem. I'm not even very concerned anymore. Im just going to let her run her course.
 
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BCSparky

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Does it look like some kind of burn caused by (sea)salt? I was experimenting a little and long-story-short some sea salt may have accidentally made it into my fertilizer mix.
 
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smorgasborg

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welp, mine froze last night. Had them under cover of an open roof, but temps dropped to 24 (10 degrees colder than expected). Now I have sallow yellowing droopy leaves. Anyone know if I can still harvest, is it a waste. The buds still look great, I was about 1 week from harvest.
 
Neonhex

Neonhex

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I had the same problem. Used sea salt to kill the snails in my garden. 4 plants looked exactly like that after a week.
 
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