Brown spots every time

[Shogun83]

On my sixth grow here over the last three years. I’ve always used Foxfarm. This time I’m growing in happy frog soil and using the trio and Cal mag plus. I have used ocean forest soil and had the same results. Lights are viper spectra 450 with 200 actual output.

Every single time I grow this happens. Starts with brown spots and then the leaves curl up and die. I’m starting to learn to just deal with it because the bud always turns out good enough for me. I always end up researching and end up thinking it’s a Cal Mag issue because that’s what it looks like to me.

I collect rainwater, and I always make sure it’s PH to roughly 6.2 to 6.5 after adding nutrients. I always water to about 20% runoff. They’re in fabric pots to help prevent any root rot. The temperatures the high 70s and the humidity is right around 60. I know the humidity could be a little bit lower but this is definitely not because of humidity.

this time the brown spot started at the top of the plant. The further down you go the better the leaves look. I’m all out of ideas so I am seeking advice. Please help and thank you.

 

[Phytoplankton]

Do you ever flush your soil to remove built-up salts in the soil from the chelated nutes? 3x the volume of the pot, plain water is fine, then resume feeding. It might not be that, but it's a starting point.

 

[FortuneSeeker]

Had same problems... I think in my case was salt buildup cause I didn't always watered with runoff, and from that PH fluctuations. I think... Maybe light to close, combined with ph problems? Can you check runoff ph ?

 

[Azimuth]

Could also be the rain water. Maybe your nutes are calibrated to regular tap water which generally have dissolved minerals including calcium in them, which rain water will not. So perhaps even though you're adding cal/Mag you're not adding enough to compensate for your water source?

I'd agree that it looks like a calcium issue, at least to me.

 

[AgedMaster]

On my sixth grow here over the last three years. I’ve always used Foxfarm. This time I’m growing in happy frog soil and using the trio and Cal mag plus. I have used ocean forest soil and had the same results. Lights are viper spectra 450 with 200 actual output.

Every single time I grow this happens. Starts with brown spots and then the leaves curl up and die. I’m starting to learn to just deal with it because the bud always turns out good enough for me. I always end up researching and end up thinking it’s a Cal Mag issue because that’s what it looks like to me.

I collect rainwater, and I always make sure it’s PH to roughly 6.2 to 6.5 after adding nutrients. I always water to about 20% runoff. They’re in fabric pots to help prevent any root rot. The temperatures the high 70s and the humidity is right around 60. I know the humidity could be a little bit lower but this is definitely not because of humidity.

this time the brown spot started at the top of the plant. The further down you go the better the leaves look. I’m all out of ideas so I am seeking advice. Please help and thank you.

Are u feeding micro nutes as rain water has no minerals there is fox farm micro

 

[Shogun83]

No, I’m just feeding it the trio and cal mag plus

 

[Shogun83]

Are u feeding micro nutes as rain water has no minerals there is fox farm micro

No, just the trio and cal mag

Had same problems... I think in my case was salt buildup cause I didn't always watered with runoff, and from that PH fluctuations. I think... Maybe light to close, combined with ph problems? Can you check runoff ph ?

honestly, I haven’t flushed because I always water with 20% runoff and it’s an Autoflower so i I figured I’m good. I did raise the light and today I am flushing with sledgehammer flush.

 

[SmokingWings]

this time the brown spot started at the top of the plant. The further down you go the better the leaves look. I’m all out of ideas so I am seeking advice. Please help and thank you.

The plants look healthy overall and if they are Autoflower than they are better than many we see when other members are looking for help or general growing tips and hints/

See if you can turn off the grow lights and use the room light or a table lamp or a way to get any white light into the tent so that the photos have a lot less purple or reds. That way the natural green color of the leaves plus the brown spots will be easier to see.

As it is, the first photo shows two probable problems. There is a third one which might just be because of the purple color dominating all the other colors.

There are bronze or brown spots on some of the leaves that could be signs of a Calcium deficiency. The Cal Mag Plus that I have noticed in grow shops or gardening stores is Botanicare Cal-Mag Plus. The dosage does look a little light considering that the amount of Calcium will be only 3.2% and I consider that to be a weak amount for these plants when they are under LED lights. Maybe mix up the Cal-Mag Plus first and then after 5 to 10 minutes add in the other Fox Farm fertilizers.

The other thing that appears to be a problem are a large number of dots all over many of the leaves in the upper canopy. They look too large to be from mites unless there is a very severe problem. But, they do look the right size to match what I have seen in photos from other growers who have had Thrip problems start. Insect damage is not as easy to see when using purple LED lighting so best to look for those problems after turning off the main lights and turning on a couple of typical white lights. Mites will be almost impossible to see without a close up lens but the Thrips should show up if they are there. Look under the leaves and on the younger stems.

Third one is possible but it looks like the veins in the fingers of the leaves are showing a tinge of yellow which is not usual and can be a sign of some deficiency of Potassium, Phosphorous and sometimes Sulfur.

I collect rainwater, and I always make sure it’s PH to roughly 6.2 to 6.5 after adding nutrients.

I prefer rain water and melted snow over my tap water even though the city water is consistently a pH between 6.1 and 6.4 plus being considered some of the best in the US. The natural pH of rain water is 5.7 to 5.9 with occasional rainfalls bringing down water with a pH of 6.0 to 6.1 which is not a problem.

The pH of the water will drift from low pH to high pH allowing all the nutrients to become available for uptake by the plant. Calcium needs a higher pH to become available. But, if you try to jump-start the uptake of Ca by increasing the pH then the plant cannot take in the minerals and nutrient that are available at the lower pH levels. The water drifts up and does not drift back down that I have read about so some nutrients just are not available.

Plus, rain water contains a lot more nutrients and minerals than most of us realize. The drops pick up the microscopic sized particles floating in the air and brings them down when the drops become large and heavy enough to fall out of the clouds.

Rainwater contains trace amounts of Nitrogen, Phosphorus, Potassium, Calcium, Magnesium and Sodium which are all plant nutrients. Many of those nutrients are in the best form for immediate uptake by the plant both though the leaves and through the roots.

This does not include the living and dead micro-organisms that are floating around in the air that will be captured by the water drops. These help give a boost to the micro population that is already in the soil.

 

[Azimuth]

The other thing that appears to be a problem are a large number of dots all over many of the leaves in the upper canopy. They look too large to be from mites unless there is a very severe problem. But, they do look the right size to match what I have seen in photos from other growers who have had Thrip problems start.

Those dots look too uniform to be thrips so I I still lean to a nutrient deficiency.

Unfortunately I have a lot of experience with those little bastards. The damage will first be noticeable as white, almost florescent spitille scattered across the leaves, in little drifts not spots and then a few days to a week or so later you'll be able to spot what look like miniscule grains of rice, and if you look really close you'll see them moving, but a loop will help you positively identify them.

But as stated, I don't think he's got thrips.

 

[Shogun83]

I just checked my runoff water and it’s 5.0.

 

[Phytoplankton]

Those dots look too uniform to be thrips so I I still lean to a nutrient deficiency.

Unfortunately I have a lot of experience with those little bastards. The damage will first be noticeable as white, almost florescent spitille scattered across the leaves, in little drifts not spots and then a few days to a week or so later you'll be able to spot what look like miniscule grains of rice, and if you look really close you'll see them moving, but a loop will help you positively identify them.

But as stated, I don't think he's got thrips.

I was leaning towards thrips too, but once I zoomed in on the leaves, I agree that the dots are too uniform, almost every serration on the leaf borders have them. I don't believe there are pests causing the issue. It's either a lockout, or a calmag thing, IMHO.

 

[Shogun83]

Here’s pictures in better lighting. I flushed it tonight with sledge hammer flush.

 

[FortuneSeeker]

Do you have a ppm meter to check just the water? Do you let the soil to dry between feedings? You need to up the ph back to 6+, but also need to change the feeding schedule. I think you are feeding to much of something that something remains in the soil. How many plants you grow at once?

 

[bluter]

looks like a couple problems at once. quick guess is mites and pm. it's something that hangs about in the environment if you experience the same thing between different grows.

 

[Shogun83]

Do you have a ppm meter to check just the water? Do you let the soil to dry between feedings? You need to up the ph back to 6+, but also need to change the feeding schedule. I think you are feeding to much of something that something remains in the soil. How many plants you grow at once?

Currently growing 3 that were planted in two week intervals. The other two are beautiful but in my experience will end up the same way (with brown spots).

I check the water with a test kit every time I water. This is the first time I've checked the runoff water though.

I let the soil completely dry before the next watering. I used to do the finger check but now I just lift the pots and when they are lights a feather, I water.

Can I up the soil PH by adjusting my water a bit high when I water it or do I need to sprinkle some dolomite lime on top of the soil?

 

[SmokingWings]

I let the soil completely dry before the next watering. I used to do the finger check but now I just lift the pots and when they are lights a feather, I water.

I wanted to mention that if you are following the methods mentioned in the thread on "how to water a potted plant" the part about waiting until the pot feels light weight is for when the plant is in the vegetating stage.

When the plant is flowering the waiting till the soil is very dry is not recommended. Instead the pot should be watered when the soil just starts to get a bit dry. The grower, Emilya Green, who started that thread did mention in several msgs on what to do and how to do it once flowering starts.

 

[FortuneSeeker]

Like Smoking says. If you let the soil dry too much you will get salt buildup and the runoff won't help anymore.

 

[Wastei]

We need better info to give proper help. What do you feed them and how often? How often do you water? Fox Farm is not a very good nutrient brand for growing Cannabis IMO. None of their product lines seem complete and they have many bogus really bad products marketed to new growers like "ChaChing" and "Beastiebloomz".

If you use Fox Farm it could be anything from underfeeding to overfeeding depending on the products you're using.

Look for a complete plant food used by experienced growers like GH, Dyna Gro, Jacks, MegaCrop, Floraflex and Canna to name a few. Fox Farm is sadly marketed to the youngsters and novice growers.

Cheers!

 

[Th3Grow3rNooB]

Hi mate, im new so take me with a grain of salt. Have you changed strains at all whilst this issue has been around ? Or is it the same run ? I only ask because i have a very similar issue, and im leaning towards fungi..