Yellow spots on a few leaves of one plant, one leaf on other, none on third - deficiency?


I thought I would start a new thread, as opposed to just adding to to others. Hopefully, this is a question that will help others, as well as myself.

I have three plants that germinated and have been growing since September 22, when they first sprouted. They are all Strawberry Kush and are all growing in the same medium, and receiving the same nutes.

Medium is Black Gold Just Coco, with ~30% perlite added.

The nutes are Botanicare Pure Blend Pro / Grow, CalMag+, and Liquid Karma. I have also been adding a half tsp of Great White to each gallon of Distilled Water.

Earlier, I had been setting at pH range for nutes at anywhere between 5.8 and 6.2, as that is what I’ve read is best for hydro, which, if I am correct, includes coco. I have yet to see any real signs of nute burn.

In another post, I was reading this chart for uptake of nutes, which leads to part of my question.

In reading this, it looks like, in hydro, Calcium stops being absorbed at 5.8, yet Magnesium doesn’t begin to be absorbed until 5.8. Does this chart represent an accurate assessment, or is there a pH sweet spot where both Ca and Mg are absorbed?

Originally, I had some issues with one plant out of three showing yellow spots on just a single leaf. I upped the CalMag+ and the problem went away, kind of. I did notice that, while not yellow, there were some shinier spots, still green, on some of the leaves of the one plant, but all looked well.

I am including 2 shots of each plant, for opinions / suggestions: To give an estimate of the plant sizes, they are in 10 Gallon Smart Pots.

Here is the first plant. You will notice a couple yellow spots on one of the leaves. (Btw, the leaves on this plant are the largest, yet the plant is the shortest.The one leaf in the foreround of the pic is the size of my hand, yet it has become more bushy without attaining great height.) The shot does not do justice to the size of the leaves.

Here is the area that was topped on the first plant. As far as I can see, it looks ok. The yellow spots are limited to just the two leaves on this plant.

This is the second plant. The only thing I’ve ever seen with this was one tip that looked burnt, so I dropped back on the N a bit for the mix.

This is where the second plant was FIMmed. You can kind of see the funky leaf structure where the FIMming occured, but it looks like new growth is doing ok.

This is the third plant, where the yellow spots are showing up in mid growth areas. It is the tallest plant, at over 12" high, yet also not as dense as the others, with wider node spacing; however, it grows the fastest and within a few days added about 4" of new growth to the top.

This is where the third plant was FIMmed. Again, il I have yellow spots on mid-growth, it seems like the FIMmed area is branching nicely.

From what I’ve read, Magnesium deficiancy and Calcium almost look the same, so I’m wondering if I am deficient in Cal or Mag, or if it is something else?

The odd thing is that all three plants get the exact same regimen at the exact same time, yet with definite, varied results.

For the most part, stems are green and appear strong, I don’t see anything out of the ordinary in any of the containers and I mix the nutes for all three by the gallon.

As an added question, I have been giving each plant ~30 ounces of water per day, at 15 ounces in the morning and 15 in the early evening. The nutes are pre-mixed into the water, and as mentioned, I have been averaging between 5.8 and 6.2 on pH.

As far as run-off, there isn’t any, as they are all in 10 gallon Smart Pots, and I have been expanding the watering area asthey plants increase in size. (This was suggested by the local hydro shop, as a awy to limit stress, yet also provide proper water / nutes as the plants grow. I have not watered toofar out, as I waas concerned about cutting off oxygen to the roots as they expand in the coco.

Any help is appreciated, and thanks for reading.

Barring catastrophe, I would like to take some clones this week and thin out the lower growth. Opinions on that are also welcome. :smile:

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5.8 and 6.5 are the sweet spots, respectively.

Just because you are giving each plant the same thing, this doesn’t necessarily mean they all have the same thing in their root-zone.

Testing the run-off is one of the best ways, and the most common and easily used way.

The other way to test pH and nutrient concentration in the soil , and is explained here in Robert’s blog:

You can do what your local hydro store recommends, as far as expanding the watering area. However, watering as often as you are, and you are likely actually over-watering, especially with only about 30% perlite added.

The best way to water, or feed (and probably the most common way recommended), when you do feed, is to actually learn the feel of the weight of the container with fully wet saturated soil and plant, and with totally dry soil and plant. Then you would water the entire container to saturation (this is when you’d take your run-off samples). Then you do not water again until the container and plant feel very light, but the plant has not started drooping yet from a lack of water. This wet to dry cycle in the soil is very beneficial for the roots and ensures they get a lot of oxygen, which is much needed in the root zone.

Although generally expanding the root-zone is a good practice to try and get the roots to use up all the available soil, in these fabric containers, they help keep the plant from becoming root-bound and growing only to the bottom, the extra air introduced to the soil is not only beneficial for oxygen in the root-zone, but the air at the walls of the container helps the roots “self prune” and send root shoots in all directions, making much better use of all the soil in the container.

Personally, I’d still do at least one transplant from a smaller container for a better developed root mass before going to the larger container.


@MacGyverStoner, Thanks for all of the advice. I didn’t do any watering / nutes on Monday, but did pick up some Earty Juice Microbladt, to add to the mix.

The info was quite helpful, but I did come up with some questions during the past two days.

As an update, all three containers were not watered / nuted on Monday; however, I prepared 9 gallons of mix, in order to water to saturation and get run-off.

By Tuesday morning, the coco was pretty dry, and the containers were very light, in weight. As mentioned, they are 10 gallon smart pots, and the plants do now take up a good portion of the actual pot, as seen in the pictures above.

For the mix, I used distilled water and added the Botanicare products, Pure Blend Pro / Grow, CalMax+, and Liquid Karma. Also added to the mix was Great White and the Earth Juice Microbllast.

This is where questions arise.

Upon creating the mix, it pH tested at ~4.8 in all nine gallons. I added about 10 - 16 drops of pH Up, which gave me a pH reading of ~5.9 - 6.0 across the nine gallons.

As the coco was ready for watering, each 10 gallon pot required three gallons of nute mix to saturate the medium out to the edge of the pots, make it heavy to lift, and produce run-off.

Roughly 1 hour after watering, I tested the run-off from each container. All three gave a reading of 6.2; however, tonight, just prior to turning out the lights, at midnight, I re-tested the run-off. The two plants with the darker green leaves, and bushier appearance had a run-off measuring of 6.7. The one plant with the few spotted leaves, mid-growth had a pH from run-off measuring 6.8.

Two odd things is that, using drops, run-off had a slight orange tinge, which would make me think lower pH, yet my monitor tested fine at 7.0 when placed into the control reagent. Is there a reason why run-off pH should increase over the course of 18 hours?

Also, should I not pH-up, and use a liquid that is lower in pH, in order to adjust for a potential rise in pH?

The other suggestion I received from a few folks, was to use the Liquid Karma / Microblast as a foliage spray, in order to get some nutes directly to the upper parts of the plants.

Any suggestions / help is appreciated.

On an added note, one thing it seems is that the two plants exhibit the Indica qualities much more strongly than the third plant. One thing suggested, was that, due to the hybrid genetics, the third plant could be exhibiting a variant of the genetics, and also may need a slightly different feeding regimen.

The third plant, while it does have lighter leaves, has grown exponentially taller than the other two. I had the LED 24" above the three plants, and within two days, the third plant grew ~6", so I raised the LED to put it back to 24" above the plants. As of today, plant three has grown another ~6 inches, and is just shy of two feet tall, in just one month of growth. Seeds sprouted on September 22nd.

Oh well, thanks again to all with the advice. It really helps. :smile:

I agree, sometimes different plants are more sensitive to nutrient or pH imbalances.

You might need to be really watering/feeding more, to get a good bit more run-off. It is ok if you way over saturate, in fact some people over water or over feed the day they do water or feed, until about maybe 30-40% runs off. This is often referred to as DTW, or drain to waste. The over watering/feeding actually is beneficial, it washes out extra built up nutrient salts and keeps things kind of clean and balanced. So for example, your plant is using too much of only a few of the nutrients in your mix and maybe not enough of another, so in the long run too much of some are left in the soil, this feeding and flushing at the same time helps prevent that imbalance from building up too much.

This practice will help keep your pH stable as well as avoid nutrient salt build up and toxicity. Over water/feed until 30-40% runs out as run-off, and then you’d have a significant amount to test the pH. Of course this might seem like too much, especially with 10 gallon pots, but you can get creative and adjust and make this technique work for you, use common sense and maybe only do the 30-40% flush every so often, or maybe more flushes with plain pH’ed water.

Yes, the link in Robert’s blog shows how to test only a small amount soil and water and would be accounting for any change over time as he says he has the soil mixture to be tested sit for about 24 hours. But you might not have to do it that way if you practice the DTW technique that comes highly recommended for "potted " plants.

Lets think about and analyse your results.

You want around 6.0-6.5 for a soil-less mix (i.e. coco), or 6.3-6.8 for soil.

If your run-off is lower than what you started with, then you subtract the difference from what came out.

If it goes in the top at 7.0 and comes out the bottom at 6.0 your pH might be actually 5.0

If run-off is higher than what you started with then you add the difference.

If it goes in at 7.0 and comes out at 8.0 your pH might actually be 9.0

So ideally you want about the same thing coming out the bottom that went in the top.

You put 5.9ish into the top. Most came out at 6.7 and one at 6.8, and then as high as 7.0 later. So your soil has stuff in it that is bringing the pH up. So you have a difference of 0.8 to as much as 1.1 and this means that this much is being cancelled or used up in the soil, so actually your soil might be as high as 6.7 + 1.1=7.8, or maybe even 7.0 + 1.1=8.1

Now this is a loose guide to get just an estimate, and not necessarily entirely accurate, the actual soil pH might not be actually as far off as the math might suggest, but it will give you an idea and if you want to verify it, you can test samples of soil after sitting for 24 hours as described in Robert’s blog.

Hope this helps,


@MacGyverStoner, thanks again for all of the great info, and suggestions. When I picked up the Microblast on Monday, the local hydro store also suggested running straight pH’ed water every third time or so, and giving it a good flush, much in the same fashion as the drain to waste you mention. I think I am going to start doing that, particularly now that the plants are really filling out the pots.

The pH examples make a lot of sense. The one thing I was confused about was the time at which I took the pH sample.

As an example, I had one or two gallons that were closer to 5.8 or 6.1 out of the nine gallons of mix I ran through the post. (Three gallons per pot, which game me good run-off. (Almost a little too good. :slight_smile: ) For the most part, each gallon pH’ed at ~6.0 after the addition of .5 ml of pH Up, or ~10 drops.

This ~6.0 water gave me a very good runoff, and it pH’ed at the bottom at ~6.2. When I tested the runoff the next morning, it was the same runoff that had been sitting in the bottom of the container all night.(I think if I would have had any additional, or new run-off, it would have overflowed the plastic trays the post are sitting in.

It was that nutrient mix that sat overnight, in the trays that then tested at a pH of ~6.7. The only explanation I could find online for this was a few people speaking of liquids that rise in pH over time, while in a DWC. The reason given was suggested that the water out-gassed the nutes, and caused the flucuation in the pH. SOme of the people in the thread mention that they redo their DWC water every so often, in order to keep the pH from creeping up. Other than that, I’m not sure why my runoff that waas sitting in the tray overnight had such a spike in pH. Is that a normal occurance?

This is definitely a a learning experience, and everyone has been very helpful along the way. I appreciate all of the suggestions, particularly the drain to waste, as I am going to move towards that for the rest of the grow. (That is actually my original desired setup; however, the size of my tent, at 1 meter squared, didn’t really afford me the space to set up the equipment to have proper drainage. I did see a number of great setups on YouTube that had the drain to waste system.

On an additional update, I used the foliar spray this morning that I made last night, and so far, the plants seemed to respond well to it, or at least are showing no outwards signs that it was a bad idea.

Thanks much, again. :smile:

The sitting liquid was probably just leaching more of the alkalinity out of the soil as it sat at the bottom, I assume it still was touching the bottom of the bag and had contact with the soil inside.


@MacGyverStoner, yeah, this is true. The liquid was up against the bag, and wold have had indirect exposure to the coco; however, the coco that was at the sides of the bag had never been watered.

One of the reasons I chose the Black Gold Just Coco, was that, supposedly, it is prepared in advance to be usable right out of the bag, and not be rinsed first. I’m not certain of the actual pH coco would be directly out of the bag.

On a side note, could the actual bag, “Dirt Pot” brand have any alkaline levels in its make-up? Other that PETE, I’m not really sure what those bags are manfactured from.

I’m going to keep a close eye on the pH, and as suggested, try to run a decent supply of liquids through the medium. I’ll keep everyone posted, and thanks again for all of the help and suggeestions.

What lights are being used, area of tent and how far to away from the tops?

Just want to know for interest sake because I had similar looking problems even though my PH seemed stable at 5.8. After dropping it to 5.6 some of the purple petioles turned green which is good and the plants are looking better but new leaves keep coming out thin and light neon green unless I adjust the light.

In a 3x2 area I was using 400w because I’ve seen many grows using the same but my plants just hate the extra light. Running a 250w now at 1 foot away from tops and they starting to look much green and healthier than before and finally getting some stretch (something that hardly happened before). Thinking of adding two 50w UFO LEDs after week-4 just to get tighter buds but not sure if its a good idea.

Looks like heat stress to me, but I am 1/2 blind. A lot of info here. :slight_smile:

@Lyla, My light is a Platinum LED P600. It has a total real watt output of just under 400 Watts. The reasons I chose that one was three main reasons. It’s full spectrum, and has a dual switch that allows me to run just Veg, at half the wattage / intensity, or add in Bloom, which broadens the spectrum, light intensity and wattage. (The Veg Only was beneficial in seedling / early veg transition from T5.)

The third reason was the footprint of the light, which is 36"x8" overall. This will allow me to add a second light and run them side by side.

My tent is 40"x40", which is ~1 square meter. The height is 72".

Overall, I’m satisfied with the setup, as it covers my three plants well. The manufacturer claims the coverage are to be 5’x2.5’ @ 18 inches above the canopy in bloom. In Veg, the recommended distance from plants is 24".

The only thing I didn’t account for is one plant growing taller at a faster rate. By the time to flower, I may need to place something under my one plant, which is quite full, and bushy, but shorter, with tighter node spacing.

The plants are 16", 14", and 10" tall at just shy of five weeks. They sprouted on September 22nd.

@latewood, I have had to raise the light quite often. The one plant is growing much faster. :smile:

Over the past few days, temp inside the tent has been averaging mostly 81 degrees, with just a couple hours a few days ago at 84.

After about 7PM, when the sun dips, temp drops to about 79, with a “lights out” temp around 72.

Humidity has been constant recently, at between 52 - 56%.

By the time I’m ready to flower, cooler temps outside, and the end of hurricane season should drop my humidity to about 40%.

81 degrees? Is that normal for an LED.

Sorry I don’t have much experience with LEDs but I thought they would run much cooler.

@Lyla, it is less the LED, and more living in a tropical / sub-tropical zone. :smile:

The daytime temperature here has been running around 88 degrees, with ~75% humidity outside.

During the day, and with fans running, the best the A/C can give me is 81 degrees. It does keep the humidity down, at least. :smile:

It won’t start cooling off here until ~January, but when the hurricane season ends, there will be a somewhat steady high pressure zone that should keep rain and humidity down outside. Still about a month to go. :smile:

Overall, I would say that the LED adds less than 2 degrees to the ambient room temperature.

As an update, running nutes through in a drain to waste fashion, combined with using a foliar spray on the leaves, has the third plant getting a deeper green to the leaves.

The spots are, at least since gaining insight through this thread, has limited the spots to the original leaves in question.

New growth does still have me raising the height of the light almost daily. I am going to train some of the growth through LST. I may even top one more time.

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