Hi all, I think I’ve done a “nute burn” on a plant (curling, brown + crispy tips all over the gal). The thing is, I’m using organic fertiliser. Without going into massive detail about my (only 2nd) grow, can I just ask: is there a difference between redressing nute burn in an “organic” grow as opposed a “synthetic” one? Or does one flush regardless? Because there is loads of advice online about fixing burn in a synthetic context. I think!
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Pics or it didn’t happen. 
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If you insist, @MidwestGuy! This looks like nute burn to my untutored, but lengthily-googled eyes. This whole grow’s been a mess for various reasons… but anyway! Any advice in terms of fixes, specifically if I’m supposed to do something different if using “organic” nutes, etc., most welcome and appreciated. Thanks y’all!
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Is it too many nutrients or too much light burning the tips of the leaves?
Flushing would help reduce nutrients in the soil but if the soil is still breaking down it will still be producing nitrogen and you could keep getting nutrient burn (assuming it’s that).
It’s not excessively bad and if the plant is young, it might be fine with the nutrients in a few weeks time when it has grown more.
Maybe give it a flush and see how it goes over the next few weeks. I wouldn’t worry too much though unless the entire leaf/ leaves start to turn brown. Then it’s a problem. But just the tips on a few leaves isn’t a big issue.
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I use organic nutrients and feed VERY heavily and have never had this happen. My ppfd is way north of 900. Heavy feeding requires high light levels.
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It also appears that you are in mid-flower. The plant will normally start shedding leaves as it transitions to late flower.
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Thanks for your thoughts/questions, @randylilgnome! I honestly don’t know (only my second grow). Would too much light do this to leaves’ tips also? I’ve googled “nute burn” and seen pictures that look to me like nute burn. But I respect that there’s a distinct possibility that I have assumed, and have had these assumptions confirmed via images on the internet, it to be nute burn… but that I’m actually looking at a different problem (not the first or second or third time this has happened to me already, even in my most limited experience). So I’ll look into the possibility of it being a lighting issue. One thing that makes (or, has made) me think it’s nutes, not light, is that this is happening all over the plant? Then again, @merlin44 's comment about PPFD at 900+ without issue…
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Hi @merlin44, so I’ve taken @randylilgnome 's comments on board and looked into my lighting situation. Can I preface this by saying that I know I don’t have an awesome set up, it’s the best I can afford… and it’s all I have space for.
I’m using a Samsung SF1000 EVO 100W Full Spectrum LED Grow Light, designed for 2x2 coverage (which is what I’m working with). While I understand this is not ideal, I don’t quite trust comments that say “you simply can’t grow anything with that”. Because I have. I won’t boast about having the kindest buds in the neighbourhood, but my first harvest was more than enough for my purposes and preferences. Limits are what all of us are in some ways inside of, etc.
Anyway, this plant is getting PPFD in range of 450-875. DLI is in range of 29-57 (latter values for its tallest, branch). Lower values are for the more peripheral parts. Are these values that might induce the tips of the plant to curl on account of light burn? I guess the unevenness of the readings is a) down to the light/set up; but I should also, um, admit, that there’s another plant in there, a much squatter RQS Titan, to which I’ve given pride of place in the tent. 
Its canopy is getting PPDF 720 / DLI 46 on average (except for the main cola (PPFD 1175 / DLI 76). Side question: am I doing this right? Accepting to give the main cola TOO MUCH light in order to keep the majority of the bud sites what I’ve understood to be the ideal amounts of light?
Ultimately, I’m treating the poor old Wedding Cake mean. She’s relegated to the margins of the tent, some branches pushing against its walls. I’ve thought often of just chopping her down to make proper room for the other, but somehow I just can’t! I decided to keep her and try stuff like topping (this worked) and supercropping (messed this up, starting too late and split some branches)… Maybe THAT explains leaf curl/burn tips?
The Titan is almost done, and I am loathe to get rid of the Wedding Cake also. I’ll aim to move her centrally in about a week’s time (she is indeed in early-mid flower, @merlin44, but it feels like she’s been in this state for a long time, weeks in fact.) I’d like to do my best to save her, under the circumstances. Hence this thread. Sorry it’s so long! Thanks y’all, I respect and appreciate your time and knowledge!
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To give you perspective on light intensity, mid-day sun at 45 degrees north latitude is a ppfd of ~2200+. The tops of my plants are usually around 1700+ in order to get the net level (I use a SCROG) ppfd to ~900.
Ah. Does this mean that PPFD / DLI numbers are, well, not an average really, but more like a mean? i.e., I want to most productive parts of the plant to be in whatever zone is felt most appropriate light-intensity wise for that particular grow? (That’s assuming that the most productive part of a scrog set up is at the net level–I don’t know!). In my case, I’ve not done any training on the to the smaller, healthier plant, whose light as I mentioned before is PPDF 720 / DLI 46 at the canopy… but its cola is a at 1200 ppfd and a DLI of something over 70. Presumably light burn is contingent on various other factors (one thing I’m discovering quickly is that everything is connected to everything else… the first principle of ecology, I guess!), but would folks say the burnt tips I initially wrote to ask about are the cause of lighting given the numbers above?
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I consider everything above the net as the only productive area. I shoot for the lowest light level (which is also the lowest part of the plant flowering area) of ~900. Not every spot across the canopy is at the same light intensity so the numbers that I provide are estimates of average across the canopy.
Cannabis is a very light hungry plant. Look up Bruce Bugbee for detailed explanations of light intensity and light spectra.
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A 100 watt LED light is unlikely to burn the leaves unless the leaves are an inch or two away from the light or touching the light. If the light is 6-12 inches above the plant it shouldn’t be light burn. I still wouldn’t worry too much though due to it being just the tips on a few leaves.
Looking at the pictures, I just noticed the plant is flowering. It might be sucking nutrients out of old leaves to use for the flowers. This is quite common with cannabis and the plants will draw nutrients from leaves to use for flowers if there isn’t enough nutrients in the soil. You might have a nutrient deficiency rather than an excess.
Cannabis plants can take lots of nutrients and are greedy feeders. They will use more than roses or citrus and they take in lots of nutrients. Maybe give it a feed of liquid fertilizer and see if things change.
Thanks @randylilgnome! OMG this is why I kind of love this already, even though it can be very frustrating at the same time. So my lights are not that close. Meaning, I can scratch light burn from the list. So: back to nutes… Now I need to decide, too few; or, the complete opposite, not enough! How to decide, and what next? I guess I just pick a lane (either too few, or not enough) and behave accordingly… and see if things get better or worse? FWIW, the flowers seem “stuck” in this quite early stage for rather longer than I’ve seen before, albeit with limited experience of this (and none with this strain). Maybe that’s an indication of something nutes-wise? Either too many or too few?
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What you are seeing is perfectly normal. Youve got painted nails and the part that is brown and crispy is fine. Keep on growing on bro. Heres a few pics of some ladies getting chopped next week. Im 100% organic.
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I like that “painted nails”, it’s a good name for that 
However, are painted nails from too much or too little fertilizer?
If the plant is in flower or preflower have you addressed the changing needs of nutrition? Plant still needs nitrogen but the need for p and k goes way up as well as some micronutes.
Are you too feeding flower nutes yet? lots of choices to stay organic.
Looks like poaching fade not hot nutes.
if it had brown spots I would say calcium but no dots that I can see.
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From the pics, things look relatively normal to me. It kinda looks to me with the slight saw tooth tip damage that it’s from an old nute deficiency maybe.
Your light is adequate for one plant, so to speak. You can put two plants under it but neither will grow to their full potential, yield will be relatively the same as with one plant (if not a bit less due to being to over-crowded, shading bud sights = less dense buds).
Painted nails is generally from heavy nutes. I personally like to see my gals nails done up real nice!!
I use organic dry amendments BUT when I need to know, I water a little excess to get me some run-off and test the TDS. If my plant has stalled and my soil winds up testing too hot, I do a mini-flush to bring the numbers down some, and then I make sure I replenish the soil microbes with a probiotic like Soil Revival or ReCharge.
Happy growing. 
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Thanks @Pothead64. I use a few different products from a company that makes a wide variety of organic fertilisers for cannabis, and am following their schedule in terms of dosages and all that. So I’m certainly -trying- to address the changing needs. Perhaps not successfully, or so I thought. Hence this thread initially.
What I find impossible to decide still is if this is too many nutrients/too hot a soil, or too little. “Poaching fade” (that’s a lovely phrase) = too few nutrients, right? The plant is eating itself, basically?
In re: “brown spots” I saw and removed this leaf today (below–it’s the same leaf before and after I removed it, maybe a day between photos). This leaf does have brown spots that could be the start of something? I am giving CalMag at recommended dose for “maintenance”, PH the water to about 6.2-6.5, etc.
Then again, I’m really intrigued, if also quite beguiled, by @ChittyChittyBangin’s post (and thankful for it). I’d say my plant doesn’t look, overall, nearly as nice as yours, @ChittyChittyBangin. I’ve not got vibrant green or striking yellow. It’s mainly just pale green, except the newer growth/sugar leaves (which are greener). Everything else looks kinda chlorotic, and just dull.
How do I decide though? ARGH!
Thank you @d-Jawz! Next time I grow, it’ll be one plant for sure. I think I’d actually like to try this Wedding Cake again. Although it’s an autoflower, I topped it (just to see what would happen really): and it responded well I think… but I failed to take advantage of that by being ready to try anything else–can you scrog an autoflower or do super-cropping I wonder? This plant looks like it might respond well to that in the limited 2x2 space I have for it. As it stands, I’ve been bending (at times breaking) and cutting into it to make space for the F1 Titan also growing in there, which is a really cool polyploid actually. I’ll certainly try a run off test with a TDS meter… but I am for some reason under the impression that these readings are not very important when using organic fertiliser? How hot is too hot, ballpark, in your opinion? Because in my last (and first ever grow) I was getting crazy high EC and PPM readings. And while that grow was far from perfect, I didn’t see something like this happening.
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And by the way, yes, I’m a total dummy. I thought to grow these together because of what I imagined was going to be a similar flowering time, and broadly similar seed-to-harvest times. I didn’t count good. 
Oh no, I hope this doesn’t bring me all the way back to lighting… because obviously that’s been imperfect for the Wedding Cake.