Magnesium or Potassium deficiency ?

[bager]

Guys, I need help to determine what is causing this to my plant. I have two plants under LED and both are exactly one month old and since the first feed time I noticed the small plant (the one having problems) showed yellowing tips of the leaves few days after I watered with light solution of Fish mix without anything else.

My second plant is on the same feed schedule and shows no such signs whatsoever. I am feeding them with very light Advanced Hydro Bloom and Micro solution of just half the recommended amounts with PH'd water at 6.5. I first soak the pots with about 10% runoff and leave the plants to dry them out for about 5-6 days. The pots are 4 gallons fill in with Gold Label Special Mix without extra nutes.

Please help.

 

[Muddy]

The Gold Label web site doesn't go into any details about what is in their mix, only that it contains organic nutrients. They don't say what is used or at what percentage. If there's any information on the bag regarding this, it would be helpful to know. Also, have you checked the pH of your run off? What is it reading? Also, were your pictures taken under natural light? If so and we're seeing the true color of the leaves, they look a bit lacking in N. Normally at their age you should be feeding veg nutes, not bloom. That could explain the lack a lack of N.

I don't want to speculate any further until we know more about your soil and run off pH.

 

[bager]

Good point about the soil. I checked the soil bag and found the following: Perlite, brown peat, coir, Swedish clay, lime, trace elements and mineral and organic fertilizers. So it seems t hat even the "light" mix has some fertilizer additives not as I expected. My previous grow was done using the same soil manufacturer but with a soil that had a lot more nutes and the grow was quite good. About the PH of the run off water I haven't had the chance to test is as I noticed the yellowing today, and the last time I watered the plant was on Sunday. The picture is taken under natural light so the actual color is more visible compared to the LED light. As I said the initial nutrition that I added was only BioBizz FishMix in light solution - 2ml for 2 liters of water, PH 6.8. In few hours the dark period will end and I will pour the pot again to check the run off. Regarding the N, both plants are already in flowering so I cut the FishMix feedings and added the Micro solution which also has N but in lower levels.

Here is another picture:

So the question a bit changes - nutrition deficiency or ph lockout ? I guess when I have the ph run off levels we will know for sure..

EDIT:

Just got the run off water test results - the PH comes at 6.2, what do you think ?

 

[Muddy]

6.2 is a little low but not to the point where it would cause a nutrient lockout. You were feeding at 6.5, so go to 6.8 next feed and check the run off again.

At 30 days old your plants are in preflower, not fully flowering yet. That won't happen until vertical growth stops, usually around the end of week 5 or into week 6. Until that happens they should still be getting veg nutes. I suspect that the nutrients in your soil were probably pretty mild and may be exhausted by now, so the plants are hungry for some N. Get them back on the veg nutes, and maybe add a bit of epson salts, 1 tablespoon per gallon of feed. That should take care of the deficiency. Your overall color is pale. At their age they should be a deeper green color. Also, take a look at this article. It should give you a better idea of what to expect from your plants. https://www.autoflower.org/f44/life-cycle-auto-flowering-cannabis-5113.html

 

[bager]

Thanks Muddy ! However I also have now the run off water from the other plant which is doing much better and is quite bigger. The PH is 6.4 and I am thinking could it be the 2 point difference between the PH of the two growing mediums that make the other plant grow much better ? I've decided to go with a 3 liter flush of plain water yesterday. Oddly the sick plant seems kinda better today so I will wait for the medium to dry out a bit and then boost it with light veg solution. Hopefully I didn't flushed too much nutrition from the soil as the pots are 15 liters and I used only 3 liters of water with PH of 7.

I've red your article already, several times I still can't believe how my blueberry from the previous season was able to absorb 2-3 times the same nutes without any problem...Maybe its the genetics. For my next grow I think I will go with pure organic soil without any chemical additives but only homemade tea.

I will keep you guys posted on my progress, hopefully the plant will get batter.

p.s
Can someone explain to me what epson salt is ? Is it normal salt or it is something used entirely for gardening ? I cannot find such additive in my country, probably because I don't know exactly what it is.

 

[Mr ganjamoto]

p.s Can someone explain to me what epson salt is ? Is it normal salt or it is something used entirely for gardening ? I cannot find such additive in my country, probably because I don't know exactly what it is.

Epsom salts is the common name for Magnesium (Mg) Sulphate (SO4).... and you can usually get it from pharmacy's/chemists and some health food shops as well as garden centers.

Happy gardening

Mr Jorilla ganjamoto.

 

[bager]

Thank you Mr Jorilla ganjamoto ! I was able to find magnesium sulphate in the local pharmacy. Fed the plants as Muddy suggested and they definitely look better now

 

[bager]

Guys, it seems the problem is not yet resolved. Since the epson salts the sick plant thrived for a bit and I noticed new growth showing up but right now she look even worse. The taller plant is exploding with flowers...What do you think this coloration is indication for ?

 

[Grim Reefer]

Guys, it seems the problem is not yet resolved. Since the epson salts the sick plant thrived for a bit and I noticed new growth showing up but right now she look even worse. The taller plant is exploding with flowers...What do you think this coloration is indication for ?

Hey man how old is your plant? Whats your ph going in and out?

 

[Mr ganjamoto]

Guys, it seems the problem is not yet resolved. Since the epson salts the sick plant thrived for a bit and I noticed new growth showing up but right now she look even worse. The taller plant is exploding with flowers...What do you think this coloration is indication for ?

Have a look at the info sheet I posted here in this part of the forum about potassium deficiency...

Mr Jorilla ganjamoto.