This runty little auto (in week 3 of flower) is showing signs of stress in some of its uppermost leaves.
For the last week, I’ve had my light hanging 12"/30cm on 100%. This light was emitting about 900 ppfd in the middle parts, but only 350 ppfd near the edges. On the 18/6 lighting schedule I’m following, that is about 58 DLI in middle/highest spots. Too much!?! I’ve read this is too much (on the photone light meter website).
I’m wondering if I’ve damaging the plant with the light? Those parts highest/closest to the light are the ones I’m worried about. The lower leaves look nice and green, but those nearest the top(s) are paler and have rust spots.
Thanks! Some pictures attached. The first is the plant itself; 2nd shows highest part with stressed leaves; third shows a lusher, healthier looking side branch (who’s DLI has been in mid more high 20s or low 30s the last week).
FWIW, a new light arrived today, with way more even coverage. I’ve set the new light so that PPFD is between 500-600, DLI low 30s. I’ve read variously that this is a good range for autos. Any thoughts or advice most welcome though!
Are you growing photoperiods, and if so, are you talking about 1000 ppfd during flower, @merlin44? Because if so, 1000 ppfd over 12 hours is a DLI 43, which is (as far as I know) still within ideal range. I think I’ve had the stressed-out looking parts of the plants under maybe 800-900 ppfd but on 18 hours of light, which is DLI 51-58. Which is, again, too much, as far as I (now) understand. Obviously I don’t really understand this, but I’m trying to! As I say, I’ve reduced light back to within range. Do the lighter leaves look like this might be from too much light? I don’t know!
Thanks for your reply, @Truetopath. I think i began all this (not very long ago) thinking autos were somehow easier. But I’m starting to think that is not necessarily the case. The autos I have grown so far (this is only my third ever grow) have all been quite finicky. By the time I realize I’m making a mistake, it’s too late! Does anyone have any photoperiod recommendations that a) would fit in a 2x2x4 tent (it’s absolutely all the space I have to work with atm) and b) tolerate non-expert levels of skill? I might ask this question on a new thread at some point.
I started the same way, thinking autos were easier. Realized pretty quick that wasn’t the case.
For the 2x2x4 I would definitely go with a photo and keep it trained low. Leaning more towards the indica dominant keeps them a little shorter and bushier, while sativas will often be taller.
I’m running my first autos ever and I’m finding they require less nutes and light to be happy. This is with three different strains and breeders. They are also very touchy I tried training two of the four and they all broke branches. They did however take topping very well and the broke branches didn’t phase them
This looks like light stress to me. Ive never used a light meter or anything, I just look at the recommended hanging height and ppfd map and go from there.
Every plant will react differently to different amounts of light/nutes etc and will vary further with other environmental changes. I would ignore the PPFD and DLI numbers and watch the plant, it will tell you what it wants, and right now it looks like it wants less light.
Have you noticed a significant difference in growth rates in veg? I leave my 300 watt light at 75% 18 or so inches above the canopy in veg. But if the growth rate is significantly faster maybe I should just do 100%
I don’t have a real answer to your question. When I got my PAR meter, I measured the light intensity at noon. It was well over 2000. From then on, I have given my plants as much light as I could. The center is around 1500 and about 900 around the edges. I figure if the sun gives them 2000 or more, then anything that I can give them while keeping temperatures in the mid-80’s F would be fine.
