Early stage problem/possible Ph fluctuation

[leftmyth]

Hello, guys!

I think I have a minor problem, at least I hope so, but would like to know for sure what have happened and how to sole the issue. I will try to be brief, so here it goes:
At the 7th day of grow I decided to give my 4 plants ( 2 Shortstuff Snowryders, 1 Shortsuff #1, and 1 Auto Assassin) a bit of extra Mg. Here is a pic of one of Snowryders - for me it looks like first stage of Mg def. I switched to 18/6h routine and gave modest amount of Epsom Salts, 1/2 teaspoon/1 liter , through foliar feeding. After couple of day or smth I noticed some brown spots and probable Mg def symptoms seemed to intensify.
At the 8th day I had first watering with runoff with molasses - almost teaspoon per 2 liters. (prior to that 3 watering - 70, 100, 100 ml of water PH 6,5 - 6,7) Here are pics. Snowryders
#1


,and Assassin which looks perfectly fine.
Overall look:


By the way soil is - it is quite low in nutrients. Some random seedling phase soil with a bit of peat. NPK 11-18-20.
On soil package states that it is PH6-7./ Have used it before, and it was around 6,7. Now I rechecked runoff, it was:
1. water 6,7; runoff 7,1; soil 7,3?
2. water 6,7; runoff 6,9; soil 7,1?
Could it be some PH fluctuations/some hotspots due to not proper mixture of soil, low quality, something else?
After first full scale watering with runoff spotting doesn`t advance - maybe it fixed hotspot problem-, but plants look slightly too small for age.
Tomorrow (Day 13) I should water plants. Theoretically I should start giving nutes, I use Hesi TNT (NPK 3-2-3).

Guys, any thoughts?

P.S. Sorry for my English, not my native and haven`t used it for a while.

 

[namvet25]

Are you saying your soil comes with 11/18/20?

 

[leftmyth]

Well, on package is NPK 11-8-20, and N-P2O5-K20: 11-19-24

 

[namvet25]

Using soil mix with added nutes is not recommended .Your soil is way to hot for mj and that is what is causing your problems.You do not need cal/mag this early.I would stop using nutes and just use plain ph water when needed.

 

[leftmyth]

That`s interesting.
I have looked up in online grow stores specification of MJ soils, and they were quite close, if not exact, to this one.

But what about Cal-Mg - when to start that to avoid def?

 

[namvet25]

I have never seen a grow mix with NPK numbers that high and if there slow release you wont need added nutes for a long time.I wouldn't use cal/mag until she starts to flower,than use at a low dose with every watering.

 

[leftmyth]

I see. That slightly perplexes me - could there be some misunderstanding or misinterpretation. For example Plagron has similar NPK . And I have used for my first, and funnily most successful grow, soil with NPK identical to Plagron.
By the way this soil mix, not Plagron, but which I use now, is intended just for seedling phase (made for tomatoes and bell pepper), therefore should contain quite minimum amount of nutrients.

But still - in your interpretation could this Mg and some other def be caused by too much nutrients in soil?

 

[leftmyth]

Well, at the moment seems that rusty and white spots don`t spread, but intervein chlorosis is. Today is 14th day. Here is example

Is it because some other nutrients block Mg, because soil is too hot as namwet suggests, or just MG def?

Any other opinion on this issue, guys?

 

[Waira]

Hi Lefty :tiphat:..sorry for the delay,... been having computer problems:slaps:..your English is plenty good, mate!
... well, like Nammy said, pre-fertilized soils aren't recommended because of the general sensitivity auto's have to nutrients,... that however, can be highly variable, and strain specific,... older, established auto's can take it better, but seedlings are rather sensitive,...I don't see the usual signs of more severe nute' burn though- yellow/brown tips, newest growth deformed, with yellowed/dead patches, but if it's just on the edge of tolerance, there won't be, just some stunting,...I admit I'm quite surprised, considering those NPK #'s- :dunno: That said, it's very odd to see plants this young with deficiency issues, but it can happen,... (keep in mind, the soil may have NPK, but not Mg, Ca, etc.),...usually, this is a pH issue,... looking at your info, the soil is a bit alkaline, but nowhere near off enough to cause pH lockout, especially of Mg,... puzzling!..that's sure what the symptoms look like,... Oh- the spots looked to me like the beginnings of Ca defc.,.. you say that's halted now? The molasses likely helped with that (Mg, Ca, K, plus a little Fe in it),... light dosing of Ca-Mg can start at this age, if you aren't adding in other nutrients,... try a foliar spray of epsom salts, at 1tsp/L, and see if that helps,...

 

[leftmyth]

Hi Lefty :tiphat:

Hey! Thanks :grat:


Well, I tend to think that PH could be the main cause of problems. But no 100 % sure.
Just today I repoted girls and took runoff measurements, watered with bottled water PH 6,4-6,5 + mildly with molasses /1 tspoon per gallon. Runoff was around PH 7. I have read about two different result interpretation:

• One, that actual PH of soil is difference between water and runoff, in my case = 7,5 :crap:
• Two, actual PH of soil is approximately + or - 0,2 -0,3, so it would leave me with soil of 7,3.

On soil bag is stated that PH is something like 6-7. I remixed the soil, added perlite, but maybe there are some hotspots or spots with various PH level.

All I can do about that for now is water plants with lowered PH water. Maybe in future I should switch to some other medium, like coco+perlite.


On the topic of visual evidence - Assasin still looks quite good -
;
Snowryders have intervein chlorosis and some wrinkles , but ShortStuff #1 - which I grow for the first time, and which is some superfast and supershort auto - has some patches and looks like going to end its days -

Overall one


By the way - I sprayed girls on the 7th day with some very weak water Epsom and water mix for prevention - after that those spots appeared. There are some new, but just one or two per plant.
Well, the problem for near future is to understand when to start adding a bit of nutes. I have experienced something like given situation, but not so severe, and remember that one point it is hard to pin the moment for adding nutes.


P.S. I grow with CFL, but have one small LED for plants. Like this . Some 10W. What was the safe distance to avoid possible bleaching?
I have read about it, but have unfortunately forgotten, and most of topics and articles cover big lead panels issues.