So my sister's boyfriend decided to grow some plants, and neither of us have grown before. Anyway, there's starting to get yellow leaves and brown spots. I've read up on all the light cycles, when to water, nutrient ratio etc. From what I first read I thought the yellowing leaves could be nitrogen deficiency, but we've been feeding them with 5-1-1 NPK nutrients. When I try to look up what the problem could be I just get overwhelmed by 20+ different things that could be wrong, so I figured I'd ask some experienced growers. I've added some pictures of the plants and the grow setup. The light is 600W HPS. Any help would be greatly appreciated, thanks!
That looks like a little nutrient burn. Maybe the soil doesn't have proper drainage or the roots are bound but maybe lockout is causing the leaves to decay.
I made sure the water can drain out from the pots, so I'm guessing the other 2. I'm pretty sure he's just been following the instructions on the bottle for the Fish Fertilizer. What is the proper PH level? From what I've read it should be between 6 - 7 PH, and every time I check the soil it's never above 7.
High! When the leaves curl up taco style like in that one photo, is indicative of heat stress. The other yellowing/brown spots could be calcium/magnesium which some cal-mag should correct. You can judge... Calcium deficiency: Magnesium deficiency: Heat Stress: *edit: ensure your pH. is correct.
6.5 technically but yeah the runoff is important because of the buildup of nutes throughout the cycle. Usually the runoff pH goes down over time and people end up with lockout near the end.
Alright, gonna move the light up a couple inches. What is the best form of Cal-Mag for feeding the plants?
Someone mentioned nute burn... this could also be a problem. they sure look burnt don't they. but, to answer your question, i guess cal-mag is cal-mag but cal-mag plus from botinicare? i think? is good. have used that. *edit: if you suspect lockout conditions, just feed once with plain water... no nutes, same amt of water. doing a light cycle of plain pH.'d water before beginning a new weeks feeding schedule will help prevent lockout conditions.
i ain't no guru so unsure about the cal-mag causing nute burn. i think i would probably go ahead and give them a regular dose of plain ph'd water (this sorta resets everything), let that dry out real good, and start feeding again. also, a foliar feed with plain, unscented, unflavored epsom salt (magnesium sulfate) may help the mg. but i do not know anything to add for calcium. if you foliar feed (~1 tsp./gal.), do it at lights out so it won't evaporate away as fast.
Alright, gonna do the plain PH watering and let it dry out like you said, then I'll go from there and try some cal-mag and see if that helps. Thanks for your help!
anytime. you might can foliar feed with cal-mag (see label) while waiting for it to dry out. then just make the cal-mag part of the normal feeding program. 'tis what i do.
also... the weekly dosages on the nute labels are for the entire week... not each feeding. divide that by the # of weekly feedings (typically two). start with a lower dosage, like 50% max recommended and increase it a little each week until the tips begin to burn or you reach full strength. if the tips begin to burn, back off the nutes a bit.
Good to know, I'm pretty sure he's been using the full dosage, so I'll be sure to cut it back. Gonna try out everything you said, so hopefully we see some improvement soon.
in that case, you may want to go ahead and flush it out real good using 2-3 times the container size of water. wash that crap out. keep us posted!
Will do. I think he's only been feeding once a week, but I don't know for sure. I'm sure it can't hurt to just flush them out anyway just to be safe considering they look pretty burnt. I'll post back in the next day or so and let you know how things are going. Thanks again!
I like GH calimagic for a cal/mag supplement. It's only a 1-0-0 so 1% nitrogen. That doesn't add too much to the nutrient schedule. You definitely have a lack of calcium brown spotting. Some of the cal/mag supplements out there are 4% nitro. I would look out for that and avoid too much nitrogen especially.
I don't think that's nutrient burn. The light is too close and you can tell that by the serrations on the leaves curling up towards the top of the plant. Nutrient burn starts at the tip of the leaf. It then progresses to the tips of the serrations on the leaves and then envelopes the whole leaf with yellow/red then brown. The random brownish spotting is more sign of deficiency. Either phosphorus or advanced calcium deficiency. The other thing is those look like bottom leaves that are old and no longer getting good light. Sometimes the plant self prunes them off and they just kinda shrivel up like that. They could have been bumped. It doesn't mean there's anything wrong with the plant.
Here's phosphorus deficiency. It looks very similar. The other small spotting is calcium def. Cannabis Phosphorus Deficiency - See the Symptoms & Get the Solution! | Grow Weed Easy
Organic growers use crab meal, bone meal, kelp meal and other ground shells for calcium supplementation. You can find these at your local garden store as well as a hydro type cal/mag supp like GH calimagic.