1st grow. Puzzled. Please Help!!

[Jorje]

Hey! I've been searching eveywhere but I am still not sure what is wrong with one of my friend's ladies, I hope you can share your expertise with me.

He's currently on day 33, growing a group of auto sativas, 3 Monster and 3 AK-47 from a local breeder.
2 of the Monster are ahead from the group, started showing white hairs 14 days ago. The rest of the group only 4 days ago. You can see clearly in the pictures that 2 are budding nicely while the rest are just beginning.

Temps have been on the high side being summer over here. Around 90 degrees inside the tent. Humidity around 50%/60% .It's a 5 sqft tent under a 400watt cooltubed MH lamp. Exhaust is more than covered by a 400 cubic feet/minute turbine (minus scrubber and duct turns). There's an oscillating fan over the canopy and an intake fan.

Growing on NPK mixed soil. Didn't do any feeding for the first 2 weeks, only some root stimulant. On day 17 watered with 1,5 ml/L veg nutes. A mild nute burn appeared at the tips of the new growth. Didn't add any veg nutes until day 22, 2ml/L, mild nute burn again. Last time nutes were added was on day 32, 1ml/l, no nutes burn this time.
Watering is being done with tap water, left in open containers for a few days to remove chlorine, ph'ed to 6/6,8. Run-off water is around 5,5.

Light schedule has been a bit irregular due to the heat. 24/0 on nice days, 20/4 on hot ones keeping lights off on hottets hours.

Well, atfer the long introduction the issue: as you can see some of the leaves of the plant are showing brown spots on the edges and clawing. The obvious cause of the clawing would be nitrogen toxicity, but he has been easy on the veg nutes and the brown spotting should be indicating something else. Any clue on what could be the cause?

Aside from this. The two plants that have more developed buds have stop vertical growth (only 8 inches with LST, some nice budding sites though) think that they are ready for flower nutes? Should he change to HPS and risk stretching the rest of the group?

 

[Jorje]

One of the leaves is also starting to show some yellowing on the edges, maybe this can help determine the issue too.

Thank you very much in advance!

 

[Waira]

Jorje-- what do you mean by NPK soil? Auto's tend to dislike rich soils in general, and as seedlings especially,... clearly from the reaction to mild nute' inputs, it's hot even for mature plants too, and that's what most of the symptoms are, nute burn on tips, "teeth" and margins,... Heat and RH are too high as well, exacerbating this,... as the plant draws more and more water, nute's come with it, and can become too much cumulatively,...
pH of inputs is one thing, in-pot ph is another altogether! testing striaght run-off, especially from nute solutions, is totally inaccurate though the strength of the acidicfication tells me the in-pot pH is too acidic as well,... part from the soil itself, and the inputs which are acidic as well; A proper pH of the soil needs to be taken, and unless you have a quality soil pH probe, you're have to do the run-off test and calculation, which is a PITA and is still a dubious estimation,... but this method does address some of the error sources if followed carefully!-- https://www.autoflower.org/threads/...-testing-and-ph-estimation.41733/#post-928975
... any plants with fuzzy crowns should be on bloom nutes (if any due to soil hotness) and under HPS,.. the others can come along for the ride as well,... I don't know how much stretch to expect, in either light type, that's something you have to get from the breeder,.. what F generation are the AK's at? Sativa-dom's tend to take longer, stretch more,...

 

[Jorje]

Yep they are on enriched peat soil, it is supposed to have 1,5grams/litre of NPK fertilizers (dunno the proportions) plus micronutrients. Seeds were germinated on jiffys and then were put on 3 gallon pots. Reviews of the soil were very good and there were no nutes issues until the 1st veg feed at week 3 (1/4 potency) but next time they are going to regular self prepared soil to know exactly what's in there. The PH of this soil should be 6.0/6.5, that's how its advertised, I still have some unused so I'll do a test. Thank you for the link, I will try with that method.

Can't do much about temps, however we noted that the HPS seems to be heating the room a bit less, and checked the manufacturer specs and MH's bulb temperature was 1112° vs 842° on the HPS, guess that will help a bit. About RH, cant do much without a dehumidifier I guess, It will be pretty bad to have those numbers during flowering so if you have any trick to keep RH down pls tell me

No idea about which generation are the plant's at, its a local breeder that has been getting some positive reviews, but probably for next grow will just get seeds from one of the big guys.

Thanks a lot for sharing your experience!

 

[Waira]

... well, the thing is, there are other ph influencing factors in that pot, beside the nutes,.. the microbes and the root zone itself alters pH during nutrient uptake,... that's why there's not set-it and forget-it with pH!

 

[Jorje]

Hi Waira! Thanks again for your input!
Did the PH test (as good as possible) and the run off was around 6,5, so I guess everything is good there.
However, things have progressed. I am suspecting of a potassium deficiency. RH has been pretty low (curled leave edges on other plants that are on vegetative state) which is a hint, and this is how the ladies are looking.

Could this be potassium deficiency?

Thanks a lot in advence!!

 

[Waira]

... pics mostly show likely P defc., but there's some overlap in symptoms sometimes with Ca defc. (broader patches/spots of dead tissue); the one with the yellowing at the margin teeth look like K defc. to me,... what have your nute inputs been? If low, I'd say a PK booster or stronger bloom nutes are needed, and Ca-Mg too,...

 

[Jorje]

Thanks again for your kind help!

Been easy on the nutes because of the hot soil and due to the plants reaction to veg nutes, but it seems that either the nutes on the soil have been depleted, or it was mostly nitrogen then.
When the pictures were taken the plants were 42 days old. Started with flower nutes (4-8-9) on day 35 at 1/4 strenght, then on day 37 at 1/2 strenght, then on day 41 gave them a phd water only session. The schedule was fucked up at that time they were 4 days without watering, one of the plants was well, the other one was a bit droopy.

Also sprayed the plants on day 33 and 38 with Delta 9, a flower stimulant composed by:

Algae extract Ascophyllum nodosum 9,5 %
Nitrogen (N) 1.5%
Phosphorus (PO2) 4.0%
Potassium (KO2) 3.0%
Magnesium (MgO) 1.0%

Microelements

Sulphur (S) 210.0 ppm
Boron (B) 27.5 ppm
Barium (Ba) 25.0 ppm
Cobalt (Co) 8.0 ppm
Copper (Cu) 126.0 ppm
Manganese (Mn) 70.0 ppm
Molybdenum (Mo) 1,2 ppm
Zinc (Zn) 115.0 ppm
Calcium (Ca) 3.0%
Iron(Fe) 0,7 %
Cadmium (Cd) Traces

The first set of pictures when the thread was opened were taken on day 34, pistils appeared on day 20. Maybe the soil really lacked PK and the little girls starved until day 35 when flower nutes were first added, then the 4 days without watering from day 37 to 41 aggravated the situation..

 

[Waira]

...yeah, a dry-out messes with pH as well as uptake of nute's! ..let's see what the spray and bloom nutes do for a few days,... symptoms should slow and halt soon...

 

[Jorje]

Hey guys, here I go again! Thank you for taking some of your time to help us.

I am probably just overthinking things, but we found something odd while tucking leaves.

Two of the plants are completely stunted and only about 8 inches high. This didn't prevented them from making bid bud and things will probably end well for them (well, they will die anyway, good for us I guess XD).
However, since they are to short and there is such short place between nodes, the buds seem to be growing inside each other. At least this is what it looks like to us inexperienced growers.

Basically, when pulling leaves to the side we moved one of the buds and saw that instead of being one big bud, it is composed from many buds from different nodes, and that there were some buds "hidden" below others. Those buds are less developed and look lime green compared to the dark green of their counterparts. So what we are wondering is if this is normal bud formation, of if because nodes are so tight there can be some buds that are not getting enough light. If so, could they benefit from us pulling them carefully away from their upper brothers? Will they mature better if they get direct light or this is just normal and they will develop anyway?

The pictures do not really show what I am saying very well. Some buds are really light green hidden below other nearly finished ones.



Thank you in advance!!