Any ideas on what my issue is?

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This is my first grow, and I was wondering if anyone could look at the close-up picture of the leaf and tell me why it has that “rusty” spotted appearance. I’m growing Jack Herer (front right), Northern Lights (rear center) and Amnesia Haze (front left). There is a bit of this happening on all 3 of the girls, but it seems to have impacted the Jack Herer more than the others.

Seeds were acquired from ILGM. I sprouted them in water, then put in Rapid Rooter plugs in a Super Sprouter under a 24w flourescent light that came with the Super Sprouter kit (tent, lights, trays, domes, heating pads). During this stage, they got “interrupted” and went into “hiding” for a few days without light. I was concerned they wouldn’t make it (too much stress), but decided to go ahead and throw them in my grow tent. I originally had 5 started, but 2 of them didn’t survive through the seedling stage due to the “unforeseen stress” they underwent.

Once I was able to take them out of hiding (LOL), I transplanted the 3 “survivors” to 5 Gal fabric pots. I do have an Active Aqua Root Spa 5-Gal (8) Bucket system, but under the circumstances (not sure if they would survive) and being my first grow, I decided last minute just to throw them in soil and see what happens. I’m using Fox Farms Ocean Forest potting soil.

Eventually I want to get to “perpetual harvest,” so I have 3 tents with different configurations/lighting (plus a drying tent), but with this grow I decided to take them all the way through the grow cycle in my primary/flowering tent.

My Primary/Flowering tent is a Plant House 5’x5’x73" with a California Light Works Solar System 1100 UVB with programmable Solar System Controller.

Based on manufacturer recommendations and lots of research, I set my controller as follows (15 min Sunrise/Sunset is ON so the lights come on and go off gradually; R= Red Spectrum, W=White Spectrum, B=Blue Spectrum):

PREVEG1: 1wk + 4days / 39R, 49W, 99B / 18hrs on
PREVEG2: 3 days / 37R, 85W, 99B / 18hrs on
VEG1: 3 wks / 50R, 99W, 99B / 18hrs on
PREFLR1: 2 days / 75R, 99W, 75B / 17hrs on
PREFLR2: 3 days / 90R, 89W, 60B / 16hrs on
PREFLR3: 2 days / 99R, 99W, 39B / 15hrs on
FLOWER1: 5 wks + 2 days / 99R, 99W, 39B / 12hrs on
FLOWER2: 3 days / 69R, 99W, 69B / 12hrs on
FLOWER3: 2 wks / 39R, 99W, 99B / 12hrs on → +UVB
FINISH: 2 days / 39R, 99W, 99B / 6hrs on → +UVB

They are currently in PREFLR2. I had some controller issues early on (operator error), so even though we should be at 39 days based on the lighting schedule I programmed, we’re actually at 46 days under the lights in the “big tent” right now (spent 5 extra days under VEG1).

The temp in the tent is consistently in the 72F (lights off) to 78F (lights on) range, and humidity is in the 52%-55% range (was in the mid 40s, so I added a humidifier).

Air coming directly into the tent is filtered through a Can-Fan 6" intake filter. I have also installed a CAP600-UV “whole house” Air Purifier in the “Grow Space/Room,” that houses the grow tents. This purifier produces “hospital grade” air with a Pre-Filter, Activated Carbon Filter, 99.97% efficient HEPA filter and an ozone-free, germicidal UV disinfection lamp. It recirculates the air in the grow room/space that the tents are housed in to keep the environment clean and combat odors. I also have a 6", 400CFM fan w/Charcoal Filter that pulls air from within the tent and evacuates it directly outside.

For nutrients, I am using the Fox Farm “Dirty Dozen” and have been feeding according to the chart provided by Fox Farm for growing in Soil.

I bought a RO system, so I can produce clean water, and I mix my nutrients 5 gallons at a time. Basically, I run 5 gallons of RO water in a bucket, adjust the pH to between 5.6 and 6.8 (Fox Farm’s recommendation), then add the nutrient mixture, mix well…and re-check pH and TDS.

I did screw up early on, and hit them with a massive dose of Fox Farm Big Bloom (Worm Castings & Bat Guano - 0-0.5-0.7). Basically, I screwed up my calculations on how much to add to the 5 gallons of water…and ended up using 4x more than the recommended amount. After I realized what I had done, I was concerned I would have some sort of “nutrient shock” so I did water with water only (no nutrients) for a few days.

It was shortly after this screw-up that I first noticed the rusty/yellowish spots on some leaves.

So far, I have been removing any of the leaves that develop the rusty, spotted look. For a few days after I do, they seem to thrive with new growth and look great (as far as I can tell anyway…this is my first grow :slight_smile:), but it inevitably comes back.

Anybody have any idea what it might be and suggestions to try to fix it? Also, any suggestions/tips based on my setup would be greatly appreciated.


I would use water only for a week Maybe 2. Then restart feeding. What do you guys think? @hoppiefrog, @cid,@devjyarn,
@scotty17, @kapouic, @oldguy


Thanks @fifth

After all the input from everyone here, a bit more research, and testing my run off - I think I may have a bit more severe over feeding issue than using water only for a week or 2 will fix. More detail to follow…

@oldguy Fox Farms DOES have recommended flush intervals - the first of which was at 4 weeks (which I missed). And now that I have some issues and am paying closer attention to things, I’ve realized I’ve been watering/feeding too frequently and not enough volume when I do. I didn’t pay close enough attention to detail in the FF recommendations and have been watering/feeding 2-3 qts every other day (produces no run-off) vs a heavier watering/feeding twice a week (with run-off). A complete “newbie” mistake…but we live and learn.

In hindsight - and not having any growing experience at all (not even for houseplants LOL) - that just seems like it’s a recipe for disaster (nute burn). Unless I’m crazy, what I’ve been doing is a great example of what NOT to do :slight_smile: as it just keeps piling on the nutes and because I don’t water enough to ever get runoff, the nutes just keep accumulating in the soil and become more and more concentrated with each watering/feeding cycle.

I did “over-water” at 1.5 gal per plant this AM with clean RO water (5.8pH & 1ppm TDS) with 5ml per gallon (1/2 the mfg rec) of Fox Farms Sledge Hammer added (removes nutrient salt buildup/wetting agent). The mix was <50ppm TDS going in and the run off ranged from 3600ppm TDS to over 4800ppm TDS. Interestingly enough, the plant that seems impacted most - Jack Herer - had the lowest PPMs in the run off.

Anyway, I will be doing a complete flush before today is over.

My plan is to flush with clean water until runoff levels are in a more reasonable range. I’m not sure exactly what that should be, but I assume I will get to a point where I see the TDS levels fall to a point of “diminishing returns” (ie: they stay in a certain range no matter how much I flush).

Once I reach that point, I plan to “feed” with nothing but Fox Farms Bushdoctor “Boomerang” - which according to the mfg is supposed to help plants recover from stresses (including mineral salt buildup) for 2-3 feedings…or until the girls are no longer developing the rusty spotted leaves - whichever comes first.

I also plan to keep them in veg until the issue is resolved.

Once they bounce back, I will proceed with feedings at 1/4 of the manufacturer’s recommendation and feed based on the recommended schedule (2x weekly WITH runoff each time)…unless of course conditions warrant more (ie: they get too dry between feedings). I’m also going to start testing TDS in the runoff and keeping a log for future reference. Would be nice to be able to know with some degree of certainty that if runoff is within a certain range for pH and TDS - nutes “should” be on point (and I assume 3600-4800 ppm is WAY too high).

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I’ve read fox farm Ocean forest soil is infamous for causing various nute burns. And I’ve also read that you shouldn’t follow any brands nute schedule to the T because they tend to overdue it on the suggested amounts. Sounds like you have everything else pretty much dialed in.


Thanks @treycer11 Originally I planned on doing hydro, so I didn’t look that much into growing in soil. When I decided at the last minute to go soil on this (my first) grow (of anything), I figured I could just throw them in pots and follow the manufacturer’s recommendations for feeding and be safe (especially using soil and nutes from the same manufacturer). Recent research into the specifics of feeding a soil grow shows you are on point. Virtually everything I’ve seen on the subject (outside of manufacturer’s websites) says use 1/4 to 1/2 of the manufacturer’s recommended amount of nutes. I haven’t seen anything specific about the FF Ocean Forest soil causing nute burns…but if I do soil again (likely) I will def look into that further. Thanks again for your help!

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@fifth. T hanks for the tag ma’am. :wink:
See. I was paying attention. :joy:

@ZenMaster. A couple more waterings without nutes or very light nutes would help for sure.
Most folks that use the fox farms nutes give 1/4 to 1/2 dose to keep from having issues.
And I believe they also have recommended flush intervals too.
So that can factor in too if not done.
A check of your run off ph and ppm will give you an indication of where your numbers are and you can proceed from there.
Peace. :v:


Potassium deficient.


if they are in soil my advice ( hope the guys tell me if i’m wrong )
as an organic version, so to speak, cut a banana peel into small pieces and mix them with the soil in which you have them.and you got potassium…
also for calcium you can make a powder from crushed eggshells also mix with the soil .:smile:

and voila


Thanks for the input @covertgrower I actually considered that some sort of deficiency (Calcium, Magnesium, Potassium) may be the issue before I considered over-feeding/nute burn - and did a bit of research - but all the leaves of plants showing one of those deficiencies didn’t quite match exactly what mine look like…it is very close on potassium deficiency - but not exactly.

However, now that you mention it, I will definitely pay more attention to minerals/mineral deficiencies.

@paco I love the idea of egg shells and banana peels for calcium and potassium. I just dug into a bit more research, and banana peels for potassium are excellent and super easy to do - just cut them into pieces and mix in with the soil (place at bottom of hole when planting for transplants). Egg shells for calcium seem to be a bit more work. Since they breakdown so slowly (even crushed), it seems the best way to use them for an immediate impact is to boil the crushed egg shells, then place them and the water in a container to steep for 24-48 hours, then use the water to supplement feedings. I will definitely be incorporating both banana peels and egg shells in the future. Great idea - thanks for sharing!


If you do have potassium Deficiency try adding mammoth p to your regimen to make potassium more available and Mobile to the plant , start off with a str8 R/O water w cal mag only maybe an enzyme to break down salts still in your roots flush and adjust Ph around 6.5-7 and check run off Make sure it’s above 5.6 when coming out if it’s above 5.6 keep feeding if under flush agin

If you’re using un buffered RO water you’re likely to run into a calcium deficiency, which is what it looks like you’ve got going on there. pH adjusting your water before having any dissolved solids makes it really unstable, and the included buffers in your nutrients might not be able to keep it within spec, which could lead to other issues.

Sounds like you’ve got a great plan and some excellent aspirations! Looking forward to seeing what you do!


@devjyarn Thanks for the input. Now that you mention it, it does make sense that RO water - being derived of all the minerals present in tap water - could create deficiencies. Will def keep that in mind going forward.

With all the input received here, becoming more aware of the “error of my ways” with regard to nutrients and feeding schedule on this (my first) grow, and comparing more pictures of leaves with various issues from around the web - I’m pretty sure my issue is over-feeding/nute burn here (especially when I add up all the things I’ve done wrong so far with regard to feeding/nutes :slight_smile:). As far as pH adjusting, I did a bit more digging, and you are correct - it should be done after I add the nutes not before. I will “fix” that immediately…and also plan to only mix enough at a time for the immediate feeding (ie: not store pre-mixed nutes…they do get kinda “grungy” looking in the bucket after they’ve been mixed for a few days). Thanks again!


Adjusting pH after nutrients are added works if done slowly but there is quite a risk of “unwanted chemistry” and pH swings. My view is that building a neutral, buffered solution before adding nutrients will give you more consistent results. I’m not arguing against pH adjusting after adding nutrients rather suggesting a way to avoid the risk upfront by building a stable “charge-environment” in your water to buffer the affect of added nutrients on pH.

Suggestion for buffering RO or tap water BEFORE adding nutrients.

1.Bring pH up to 11-12

2.Then down to pH 2-3

3.Then back to your desired starting pH (7.0?)

Boom, you now have buffered water which will resist pH swings and unwanted chemistry.

A tip on doing this very inexpensively is to buy reagents from commercial suppliers. Any concentrated base or acid will do as long as you are prepared to handle or learn how to handle liquids that are very caustic. Read an MSDS sheet, get the right gloves and eye protection and have a plan for spills… all can be found online.

Here’s what I use to build a buffer from tap or RO water…
To increase pH
Potassium Hydroxide 50%… ~$50/gallon

To decrease pH
Phosphoric Acid 85%… ~$20/Gallon. 1 drop at this strength will decrease 20-25 gallons of water by 0.1 pH so a gallon goes an incredibly long way vs buying “pH down” from a supplier.

Here are a couple links to show the products but please check the web to get the best deal… I have not done business with these companies etc. Just thought it would be helpful to show a pic and example for those less chemically inclined.

Phosphoric Acid 85% Link

Potassium Hydroxide 50% Link

Another suggestion from the trench is to get bottles with drip-proof lips. It helps with avoiding a drip of some strong reagent on the table/floor or the side of the container. It’s worth whatever you would have to pay extra if you can get it… most already come with a drip-proof lip but it’s worth checking before buying.

Lastly, I am compelled to suggest one more tip. When adding reagents at these concentrations it is always best to create a more dilute solution to work with. It’s as simple as adding the amount you anticipate using to create the buffer into 1-2 gallons of water and work with the dilute solution. This is safer and easier to hit a desired pH level without “blowing” by it.

Simplified chemistry of this buffer building if you’re interested…

The acid provides a bunch of H+'s
The base provides a bunch of OH-'s
H+'s plus OH-'s = 2 hydrogens plus 1 oxygen or H2O. If there are more Hydrogens in the water this decreases the potential Hydrogen or pH. If there are more OH-'s then the pH goes up.
Easy, so, why does this help keep your pH in line or keep your nutrients from chelating or precipitating out of solution?
Simply put, the addition of all those +'s and -'s is increasing the ability of the solution to neutralize small amounts of added acid or base (AKA your nutrients), ergo maintaining the pH of your nutrient solution relatively stable. All your nutrients in their dissolved state have +'s and -'s so if they are added to a solution with very few +'s or -'s they will have a bigger effect. Picture it in your mind like this… it’s easy to affect the mood in a room of 5 people but if there are 500 much tougher. Try cheering up the mood at a 500 person funeral or bumming people out at a big celebration… If you’re alone you won’t have much effect with your energy (+ or -) in a room of 500 people. Hope that makes a little sense.

If anyone has a better or different way of explaining buffers or perhaps a good, trusted source for these reagents tap it out. I love to learn more about things I can use.

Cheers All !


An easier way to get calcium. Milk! Use the tiny bit left in milk jug. Just add water and water the plants Immediate calcium.


What a great idea :slight_smile:

Make sure you don’t get low fat 2% milk or your buds won’t grow big and strong :muscle:t3::sweat_drops: JK …


Yeah - we def want the cheapest Vitamin D Whole Milk from 7-11 that’s loaded with growth hormones and steroids for the girls… LOL!

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@empyreal.craig this post about pH buffering :heart_eyes::heart_eyes::heart_eyes:. The concept is something I had been kicking around in my my own head but had no clue how to implement or even start that type of experiment. Your explanation is very thorough and well explained. Thank you for sharing! Very cool stuff!