Any idea what's wrong with these leaves? Feeding 800-900ppm Calmag upto 500ppm, base nutes to 700 Pk13/14 to 800-900 Using the canna Coco range. 3rd week of flower, have just stopped their height growth spurt. Is this calmag deficiency? Or nute burn? I've been slightly lazy with watering to 20% run off, usually getting to 5-10% run off atleast tho. Run off did measure 1200ppm, but I believe that's due to measuring the run off after its flowed through dried up nute water left in the tray, essentially making it concentrate.
Are you allowing the run off to remain in the tray? What pH are you using? I suggest you run a shitload of a mild nute solution with a pH around 6.0, then feed twice a day to substantial run off.
I'm PHing to 5.8-6.2 generally hitting 6.1 avg I have 4ft x4ft drip tray the girls are in on pot risers, most of the run off I'm removing with a Turkey baster but there's always maybe 100-300ml I can't get in hard to reach areas and thinly across the surface in general. Just fed them a 1100ppm feed after doing some reading it was likely calmag deficiency, measured the run off at 1200 which is a little concerning, but this could be the left over nutes in the tray after evaporation being reactivated. I'll give the tray a good clean up tomorrow, the access is a bit shit (next run I'll grow less plants haha) then maybe I'll run a lower feed say 700ppm through her twice, once in the morning once at night and measure run off.
All the other girls are healthy, the biggest girl has the issues, which leads me to think it's nute deficiency as she's getting the same feed amount as the others but is bigga
i was gonna say... are the affected leaves the ones on top? that looks a bit like light burn to me. Increase calmag?
Omega black 720W Which is set to 250W and about 1.5ft from the canopy, this is my max headroom for the light. using the photone & PPFD meter apps, they're telling me it's 900+ ppfd but I call bullshit. I found some proper light meter measurements for the light which claim 770 at 1ft at 250W, so they're likely getting 600-700 at this hight maybe, which is around 55DLI. I don't want to fuck with the light schedule as maintaining environment with lights out is difficult, I'm battling humidity. Edit: they're on 24/0 schedule
I've managed to eliminate using cal mag at all. Keeping PPFD in the 800-990 range in flower pretty much stops what to OP is experiencing from happening. Without supplemental CO2, most plants just can't handle more than 900-1000 tops. Based on my readings and observations.
I use photone, I find it to be very accurate. Based on your pics and what you've said, the plants are getting more light then they can handle. Drop the power a bit until your at 700 PPFD, once you hit week 5 flower you should be able to move it up to 850-900.
My only option is to go for an off cycle, the light is on lowest and at it's max height. I'll have to figure out how to manage the cold and humidity during lights off.
You can't really do that. You could increase the amount of CO2. Or try and move plants away from the most intense area of light.
Thanks, this is a good idea, I could move her out of the middle spot and replace her with the shortest one for now.
Well that could be part of the problem as well. Plants NEED a rest period. You'll have people say that that is bullshit, but do the research. 18/6 is the tried and true standard, though some run 20/4 for autos. But I would never recommend 24 hours of light non-stop.
Yeah I agree, I originally planned 18/6, but ran the environment for a few days before the plants went in and realised it was too much of a juggling act trying to keep the night temp & humidity stable. I'm in a cold damp basement. I read industrial grows are running 24/0, I'm guessing for similar reasons, it's not optimal but practical in my scenario.
Next time I'm going to go for 4 in this space instead of starting with 6, this will allow me to hopefully LST and scrog the girls keeping them further from the light and a more even canopy, this is my first run
imo they are just acclimating. That damage will go away. I said increase magnesium to compensate as it is well known factor in LED lighting. It isn't a big deal to increase mg, but I suggest increasing calcium as well (and iron) or you can whack out the balance. The Mg ion in chlorophyll is like Iron in hemoglobin. it's ok to fry a few leaves, in fact, I encourage it. This will elicit trichome amount. It is well known that the amount of light a plant receives is proportional to the trichome count = increased cannabinoid biosynthesis. But they still need to acclimate.
What's your setup? Lights, nutes, medium, etc What do you mean by acclimate? They've been in the same conditions since seedlings with just slight adjustments to humi & temp, they're autos. They did just near double in a size in less than 2 weeks, seems they've stopped vertical growth now atleast.