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Browning leaves

M

Mramseye

New member
Hey all. Have a couple of leafs browning through the center. First grow, Auto flowers approximately 5 weeks. Humboldt's nutes. Sunshine advance #4, 3 gallon fabric, ph in at 5.6-6.1. I used 20x mag to look all around and don't see anything moving, do I need higher x power to see any bugs? If it is bugs, any recommendations on getting rid of them? Should I be cutting any leaves that do this off? I made the decision to hold off on bloom nutes until next feeding which should be about 3 days. This issue showed 1.5 days after water/feeding. Please take it easy on my trimming job(virtually none, I have removed all leaves that were touching grow medium throughout). I just wanted to try and focus on all the other aspects of grow without throwing that in mix.
 

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Hi Mramseye
Those plants look pretty good....I'd say that's a magnesium deficiency starting to show. Have a read of the attached, see what you think. When in doubt, go very light on the nutes. Try and do a good measure of the PH of your runoff to help diagnose the issue.
 
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Thanks for the response Jeff! I have seen and read articles about magnesium def, I was thinking this was more brown than yellowing but what you sent shows same exact type pattern through center of leaves. I have been using a call/mag/iron but have been doing half of lowest number (calls for 2-5ml/gallon) I have been using 1ml/gallon, just trying to error on low side. I have been ph'ing feed waterings with a regularly calibrated ph meter. I do find my run off to normally come out about 6.6-7.0 which has never really made sense to me. throughout my grow, run off has constantly been .5-1.0 higher than in....should I be ph'ing a lot lower to lower runoff? Based on my information, should I wait a couple days and increase calmag to 2ml/gal or will that give too much since I just watered with some? Based on the article since my run off has been higher than in, doesn't seem like I would be locking it out. Should I cut these leaves off since doesn't sound like they will come back?Thanks again Jeff, being my first grow, nervous about everything!
 
It sounds like you have as real good handle on things. You're always smart to start low when adding anything, good thinking :) For now I would just up the cal/mag dose to the 2ml/gallon rate, keep PHing your water as you have been and keep an eye on these things. If you decide to make an adjustment, go slow and gradual. A good PH article is below. There is a section about How Do I Correct a Bad pH?. You can leave the leaves that are yellowing with no harm but don't be shy to remove some older fan leaves if they are shadowing bud sites.
PH Article- https://www.growweedeasy.com/ph
 
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That actually looks more like a pH fluctuation problem than a magnesium deficiency. Did you amend the soil with anything? Sunshine Advanced Mix #4 already contains dolomite lime, which acts as a pH buffer in acidic mixes (peat moss is very acidic) as well as a source for both calcium and magnesium, but it takes a few weeks of watering before it becomes available to the plants. In other words, at this stage, you shouldn't need as much calmag as people usually recommend (but still some), nor should you be having issues with pH fluctuation. Did you change anything in the last few weeks?
 
Thanks Jeff and Azorahai for feedback and taking time with this. As far as any changes, none that I am aware of. Racking my brain a couple of things that may have been a little different....first is I normally let city tap water sit for a few days, last feeding was only about 24 hours(open 5 gallon bucket), second is RH, been right at about 42-45 after last watering shot to 54, put in a small dehumid and have it down to 49 but won't seem to come down anymore today. All nutes have been the same with just small increases but last 3 waterings have actually all been same have felt it is working and if not broke dont fix until now. Jeff read article you sent, it doesn't say run off is medium PH(logic would tell me that is the case) so then I guess what I don't understand is why I am PH'ing but getting higher in runoff? Should I run like a 5ph in feeding until run off lowers? Or is there normally going to be difference between run off and "in" ph?
Humboldt nutes Base A, base b, calmag+iron, golden tree(man does that stink), plant enzymes all at half strength of lowest level haven't added flower stacker which came with kit was going to start on next feeding. Great pH chart by the way! Thanks again guys! I don't want to be a burden to anyone or beat a dead horse but have spend hours and hours researching and loving on the girls, hate to see it all go to waste.
 
When you add any kind of solution to your pot, it dissolves any solubles still present in the medium, and if you keep adding it until it starts dripping out of the pot, it'll wash away those solubles. This is why it's important (when using hydroponic/salt-based nutrients in soilless mediums) to always fertilize until some amount runs off, so that any remaining salts are displaced and substituted with the correct proportion of nutrients. Moreover, other solubles which contribute to the pH of your medium will also be washed away, resulting in a difference between the pH of what you put in and of what runs off.
Since the pH your medium seems to be drifting up, perhaps you should to either 1) flush it and immediately afterwards introduce a fresh solution of nutrients until the run-off register approximately the same ppm/conductivity of what you're putting in, or 2) "flush" it with your pH'd solution. Perhaps your mix was amended with way too much dolomite lime, so the goal would be to wash away some of it. The issue with flushing peat moss-based amended mixes too much is that you could end up washing away all of your buffers (in this case, the dolomite lime) and end up with an acidic medium, so don't do it too often and keep track of your run-off pH until it's within what you were expecting.
Or, you could just wait and see if the problem persists, but it's very strange to me that an acidic medium is trending alkaline.
 
Great talking points Azorahai. Thank you for your great insight. The exact reason I have been confused with runoff situation I have had from start. I was told by hydro store that SS adv 4 had dolomite lime(I didn't know what that was for until reading up on it later on). Everything I have read including what you are saying is if anything, In should be trending acidic not alkaline. I haven't worried about it up to this point because I was getting the numbers that didn't seem right but everything was moving along ok. I just ordered a ppm meter, think it will def help,.. I also wish I would have watered medium and checked run PH before starting so I had some type of baseline. Now that I am moving into flower seems like that is a time when certain things may be less forgiving. Maybe I got a bunk bundle of medium, but I feel it is more likey something in my error. Concerned about flushing and f-ing something else up. I am seeing issue on another plant but also only 1 leaf so far. I am going to sleep on it tonight and maybe try a small flush tomorrow. Will keep you both posted on outcome. Thanks again for all the knowledge and time!
 
I'd say that flushing with around the same volume of water or nutrient solution as the pots they are in (3 gallons) wouldn't harm them in any way, specially because there's enough perlite in the mix for good drainage and enough air diffusion through the fabric pots to oxygenate the roots. I only warned you about washing away the lime because I've done it once to correct a mistake I had made previously (topdressed my peat moss mix with waaayyy too much dolomite lime in order to fix some pH issues, which resulted in new issues), but it took well over five times the volume of the pot to remove most of it.
Do it slowly so the water/solution has enough time to dissolve whatever is in the medium, and keep checking the run-off pH so you'll know when to stop flushing.
 
I think the plants look healthy. Trying to fix something not broken is always harder than doing nothing. However, just in case, what's up with the lighting? What kind and how far from the canopy? I always look at lighting because I grew with led's too close to the plants for almost a year before I figured it out. Light burn mimics many other problems and so should always be suspect. But, as I said before, they look great to me. Good luck.
 
The plant is having issues with the soil, the PH is off likely acidic. If not dealt with it will get worse.
 
Ellisk thanks for the input. I have a bloom plus 3000LED(300 at wall actual) per manufacture recommendation have been @17-18" calls for 12-18" for flower. Have you found manufacture recommendations may be too close? When you had light burn issues did the problems show only on top leaves, or did it seem to be random?
 
Rwise Thank you for jumping in and trying to help. I know from what is said about SS advance #4 it should be acidic but that hasn't been my experience. I have been inputting 6 or less and getting 6.5-7 out. Per recommendation from azorahai I am going to flush today until my runoff is close to input. Hopefully my inexperience can be helped with all the experience and feedback I have been getting. Thanks again all!!
 
Hey all just an update. I did an approximately 5.8ph 3 gallon flush on all the plants. To add to confusion all the the first run off was above 6.5ph. after slowly flushing I was able to get run off to 6.0-6.1, still higher than what I was putting in. So I was thinking maybe it is something in the fabric pots I got from hydro store. Guy at store didn't think he had any, but went digging around and found me 5. I didn't do anything to them, just put SS mix and planted germinated seeds. They appeared to be new but maybe they weren't? Just to try and solve, I am going to take the 5th pot(empty) and run ph water through it and see if run off is similar, if it is, I have half bag SS mix left I am going to fill pot and just run PH'd water through it and see what run off is. Hopefully this will leed me to if there is a problem with the bale of medium I got or pot or something in nutes that I have been giving to the girls. In my opinion (what little I know) I do think flush has helped, everything seems to be perky with no new discolorations. Hopefully I am on track to run this out to the end. Thanks again everyone for time and feedback. If I could figure out how to share the fruits of our labor with you all, I would!!
 
Here's something i use for rinseing of roots and all my plants will get it from MJ to flowers/veggies. I will give them a good drink of epsome salts water. I just use it as a water/fert. Really seems to help snap out of a funk an greens them up a tad. Does not harm them if you use 1 tablespoon to 1gal. It's never burned them nor caused different issue just like a refresh to the soil/roots. Then go back to your feeding but don't overdo waterings. They like drier soils. This is just a tip for ya. :)
 
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