Yellow Leaves on New Indoor Grow

Hi all, I’m having a problem with my first indoor grow (from seed). Plants are 4 weeks, and three of the four plants have yellowing leaves starting with small irregular yellow spots and becoming progressively worse over the last week until some leaves are falling off of plant #3. Here is some additional info:

  • What strain: Purple Grandaddy
  • Method: Soil
  • Vessels: Pots, 5 gallon
  • PH of Water: 6.45
  • Using Hydroponic veg state fertilizer, full strength, daily
  • Indoor
  • Light system: 2x 200 watt Vivosun VS2000 LED lights
  • Temps: Day 78f, Night 71f
  • Humidity: 45-50%
  • Ventilation system: Yes, Size 6”, 440 CFM Vivosun inline fan and carbon filter
  • Co2: No

Here are my water parameters (ph of water with fertilizer, and effluent ph draining from each plant):

PH of Water (with fertilizer) = 6.45

Plant #1
Ph of Effluent water = 6.1

Plant #2
Ph of Effluent water = 6.35

Plant #3
Ph of Effluent water = 6.4

Plant #4
Ph of Effluent water = 4.86

Plants #1-3 have the yellow leaves shown in the pics, plant #4 has dark green leaves, is growing shorter and much fuller than the others, and appears very healthy.

A bit more info, one of the 4 pots (not positive which one but suspect #4) was entirely new Black Gold Organic potting soil. The other three pots have the same soil, but we’re reused after a grow outside last summer. It seems as though the plants with the highest differential Ph are the healthiest.

Not sure what to do?? Thanks for any help in advance!!





I’m willing to bet this is your issue, as the lighter 3 of 4 are showing different kinds of issues. Mainly deficiencies, possibly nitrogen and phosphorus or calcium. They look to be in beginning of flower.

You’re in soil, though? Hydroponic feed schedules usually require different amounts than soil and soil shouldn’t require feeding every day. Do you mean General Hydroponics? My suspicions on this could be totally off, so if another grower can correct me if I’m wrong. I’ve just not read of soil that needs daily feed. Coco coir requires water/feed every day.

This is reeeeally low. The dark green hints a little at excessive nitrogen, but that is a very low runoff pH.
Do you know what your PPM’s in/out are?

Thanks for the reply!

I read somewhere that it was actually best to use soil that didn’t have any of its own nutrients added so you know exactly what your plant is getting. I was actually a bit concerned that the pot with new soil would have problems because that plant would be receiving too many nutrients. You may be right in that #4 is getting too much?

I’m using General Hydroponics fertilizer which is what I used on my first and only plant that I harvested a couple of months ago. It “seemed” to come out really well. That said, I can’t actually find a feeding schedule anywhere so I’m kinda shooting from the hip on that. I did order and recently received the kit of MJ fert that is sold on ILGM, just haven’t started using it.

When you refer to “ppm”, are you referring to salinity? I did not check that but have the ability to. I’m wondering if nutrients in the new soil of plant #4 may be causing the ph to be lower on the effluent?

The fertilizer I’m using actually says it can be used for Hydro, Soil, or Coco. I’ve only been using the Flora Gro, but based on the quick growth of these auto flowers, and your observation about lack of some nutrients, I’m thinking I should add some Glora Micro to the mix to increase Nitrogen, Potassium, and Calcium?

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I use GH exclusively.
I feed once week at most usually “in soil” then as often as every other water in late flower but usually once every 3rd water is GH trio. It’s GH then cal-mag 2 watering then repeat.

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You have to use all 3 parts my freind.
Stat with the brown first mix it up then add the green and mix, then add the pink…
Thus is the exact same stuff if been using…

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Lol… I’m supposed to be using all three simultaneously?? That might explain my whole problem!!! Thank you so much!!

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I suggest you give them a good “transition to bloom” feeding. Using the chart on the back of the bottles it’s equally part all 3 at 10ml per gallon of water…
They need the micro nutrients in the brown from start to finish and the green and pink at different ratios at different stages. But it takes all 3 parts to be effective

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Remember, add brown to water first the green then pink in that order…

I don’t understand why but the scientific people say any other order makes something happen and it isn’t as good :man_shrugging:

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Ppm refers to TDS, or total dissolved solids. PPM is part per million. I’m not sure the range for GH, but in any case, too high and you can cause nutrient lockout and too low the plants aren’t getting everything they need. But @1HappyPappy got on the feeding part. You can check their website and find the feeding chart for soil. I actually have the flora series from GH unopened, it came with the 2nd hand tent stuff I have, just haven’t used it.

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This is SO helpful!!! Thanks very much for taking the time to respond and help me out on this, I Greatky appreciate it!

If it’s like Jack’s, then certain nutrients won’t mix together until diluted first. Jack’s will make a cloudy mess with little chunks if you add epsom last.

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Thanks for the tip on TDS, I’ll check out their website and then check my solution!

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It should tell you weekly feeding amounts, and the ppm ranges they amount to after mixing. Doesn’t have to be exact, but closer that better.

Copy that, Thank you :+1::+1:

What’s everyone’s thoughts about molasses? I saw a post here that recommended 1tspn per liter during weeks 4,6,7 & 9. Do I add that after the fertilizer is mixed? Do I add the molasses once, or each watering in those weeks?

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Depending on tds of water used. That transition mixture should get you around 1000 ppm give or take whatever your water is to begin with.

Idk what the ppm in your soil is right now but that could warrant lower the ppm of the solution maybe, but considering the previous feedings if soil us loaded with lots of grow.
You can flush them and start over or maybe lower the grow to 5ml per gallon instead of 10ml.
This will give you less then 1000ppm though which I don’t think us a big deal. It’s most likely just needing what in the brown and pink.

But feed GH them next time they need watered give them cal-mag water, take ppm of run off and if it’s say under 600ppm then feed the next water, if it’s 800ppm or more then may want to give cal-mag again and feed next water…
I try to keep my ppm in soil say between 800-1200ppm typically. Trying stay higher and sometimes with big plants it may hit 1700ppm in the end…

Try watch some youtube on how to use GH in soil.
It’s one of the oldest and proven products on the market so lots of good info…

What do you mean when you say “cal-mag” water. I know you’re referring to Calcium-Magnesium, but are you referring to the brown GH mix, or strictly adding CG?

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Molasses is food for soil microbes. It absolutely will not hurt anything at all to add it from time to time.
How ever, it’s mostly beneficial in organic nutrients grows in my opinion…
I do use recharge once a week or so with my GH routine though. It is all kinds of microbes and food fir them including Molasses in it…

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This stuff, sorry about that…
Any brand.

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