Help with a deficiency...

[Shmike]

Alright, these outdoor gals are showing some yellowing at the new growths starting from the middle with some brown spots about to show up. I can't tell if it's caused by Mg, Boron, or just from it getting too cold at night. I feed once a week with the Advanced Nutrients 3-part: Grow - 1.5ml/L, Micro - 1.5ml/L, Bloom - 0.4ml/L. I also add SensiZym @ 5ml/L, and B-52 @ 1.5ml/L.

The solution usually ends up at a Ph of around 6.6-6.8. The soil is Sunshine Mix #1 with a bit of bone meal and dolomite lime mixed in with it. I tested the runoff Ph and it tested at 6.7, I just for the life of me can't figure out what it is.

I couldn't tell you the Ppm of the mix when I feed because I do not have a EC/TDS meter, but I have a friend stop by every now and then to check the Ppm of the water I mix everything with, and it is usually under 80 Ppms. So I just keep that in mind when mixing up nutes. When I water in between feedings I just test the Ph which is never over 6.9 and never under 6.5.

It has been pretty chilly for the past couple of days here with the temps of the daytime dropping to 20-23*C, and before this cold/wet weather it was just clear sunny skies and around 30-35*C. at night before this Cold weather it only dropped to 28-31*C, and now it drops to around 20*C. I've seen the yellowing from extreme temperature changes before, but i see some spots about to come through making me think this has something to do with nutes.

Any help is very appreciated, thanks in advance!

 

[Core]

hia Shmike...i'm just chucking my here...but it could be that the ph of the runoff is't accurate...2 have accurate ph you should take some soil with some distilled water..and test that ....it could be your ph is a little high..and if thats not the case...new growth affected mostly means some mirconutrient problem...but i dont know witch one....
just trying 2 help out

 

[Shmike]

Hey thanks for the help Core, I used RO water for the runoff test, would it make a difference if I used distilled? If so I guess it would be a lock out problem, eh? Lol this is buggin' me...

 

[Core]

yea man use distilled ...its neutral and it will take over the ph of the soil....

 

[Shmike]

Right on dude, will do! I'll get back on that ASAP!

 

[Blackvelvet]

Optimum ph in a soilless mix is 5.6 to 6.2 so your really too high. Adjust the ph of your fert water after adding everything to 5.8 to 6

Peace Dude.

 

[Shmike]

Ah yes, that makes A LOT of sense! I just got a bottle of distilled water and tested the run-off from a sample of the medium, and it turned out to be at 6.5. I'm surprised I haven't ran into any other Ph induced problems along the way, watering and feeding it with that alkaline of water. Lol, first time with soilless, I learned my lesson! Thanks BV.

 

[floppyfundanglr]

i dont see the brown spots. Is the yellow your talking about on the middle where the growth is exploding? Cause if so thats normal the plant is just growing so rapid it doesnt get the chloriphil in it yet. Saw this in arjans grow vids on youtube. Mine all are yellow where the new growth is its totaly cool. Brown spots can be necrosis from overwatering. Have you checked that out as a potential problem?

Peace

 

[Shmike]

The brown spots aren't really visible yet, I could just see them coming, like really light lesions on the blades of the new leaves that appear like that are drying out and about to turn brown. Not something I could get with the camera very well, I can see it with the naked eye though. The yellowing just didn't seem normal to me because there is a whole lot more than normal. I don't think over watering is a problem, I never over water, if anything I underwater too much. I usually wait for them to start wilting a little bit before I water them. I haven't been adjusting for a soilless mix though, that seems to be a bit of it if not all of the problem. Thanks for the input floppyfundanglr!

 

[floppyfundanglr]

is your mix buffered with dolomite lime. This helps stablize the ph and adds a lot of micronutes, calcium, and i think mag as well. IF its a micronute def. this could help it out.

peace

 

[Shmike]

Hey floppyfundanglr. On the site it says, "Formulated with Canadian Sphagnum peat moss, coarse grade perlite, gypsum, Dolomitic lime and our long-lasting wetting agent." but I even added a bit extra dolomite lime just to be on the safe side. I just flushed them all with Ph fixed water, but I didn't drop the Ph too much, I didn't want to induce any shock. They're already starting to darken up a bit. Thanks for the help everyone!

 

[Shmike]

Here's a next day follow up, I'm already starting to notice the colour coming back and they are starting to grow a bit more vigorous already! Thanks again Core, Blackvelvet, and floppyfundanglr!