Deficiency or over-nute? Leaves look strange

[PlainJane]

E-indoor or outdoor - Indoor
E-soil, soilless, coco, aero, or hydroponic - Soil
E-specific medium - Soil + Perlite
CSL-Soil type/brand - Canna Terra Pro
SCL-Anything you have added to the soil - Phosphoric Acid to the water to lower pH a tiny bit
SCLR-Soil or slab runoff pH - originally 7.5 from the tap, I bring down to 6.8 with H3PO4
E-Age of plant - just over 5 weeks
E-Type of fertilizer - BioBizz Grow (NPK= 8-2-6)
E-Rate of application - water-water-feed, but they got it a bit early this time due to potting up, so they had 'water, feed, water' most recently
E-Lighting source and distance from plant - 250w HPS about a foot away with fans
E-Air temperature (both day and night if you are running a dark period)- 28ºc/82ºf day - 20ºc/68ºf night
E-Air % Relative humidity - bit high 70-75% the last few days, usually 65%
E-Lighting schedule - 18/6
E-Type of ventilation your room has - RVK100A1 (175m3/hour)

This seems to have gotten a lot worse in the last 2 days. This made me think it's an over-nute thing but it looks so much like some of the deficiencies I've seen that I'm not so sure. My nutes are pretty mellow stuff. Plus, other than the small one, which was given 2ml/litre (low dose), they were only just given water the last time. They are still growing quickly and they greened up after getting their nutes the last time but then this odd stuff on the leaves just happened. I was thinking Mg or Ca deficiency but I have no idea.

I looked underneath and with a crappy microscope and I don't see any pest infestations. I just see spotty strange leaves. I've had a few of those larger spots on the lower leaves for a while and attributed it to a high pH, which I've now sorted out and it seemed fine until this recent strange spottiness.

Any ideas?

Here are a couple plants that are affected:

[attachment=o204677]

[attachment=o204679]

- this is the "runt" that was given 2ml/litre (low dose) on the last watering
[attachment=o204678]
It has none of those spots previously and the leaves were more straight/unturned.

PlainJane Reviewed by PlainJane on 10-13-2008. Deficiency or over-nute? Leaves look strange E-indoor or outdoor - Indoor E-soil, soilless, coco, aero, or hydroponic - Soil E-specific medium - Soil + Perlite CSL-Soil type/brand - Canna Terra Pro SCL-Anything you have added to the soil - Phosphoric Acid to the water to lower pH a tiny bit SCLR-Soil or slab runoff pH - originally 7.5 from the tap, I bring down to 6.8 with H3PO4 E-Age of plant - just over 5 weeks E-Type of fertilizer - BioBizz Grow (NPK= 8-2-6) E-Rate of application - water-water-feed, but they got it a bit early Rating: 5

[Weedhound]

Ph level for soil (and the water you are using) should be between 6.2-6.8. Since you are only dropping your ph to the top leve (6.8) I have a feeling that your runoff ph will be even higher and that ph is your issue here.

I'd also stop giving nutes until you figure out exactly what the problem is.

[Weedhound]

also consider larger pots for them......they may be rootbound as well but I'm not sure as I'm not positive what size those pots are......but they look a bit small in the photos.

[PlainJane]

Thanks, weedhound. I can drop the pH a bit more. My run-off is always about the same as what I put in. No plans for nutes until I figure it out.

It really does look like a calcium deficiency from the photos I've seen of it but then it also looks a little bit like a magnesium deficiency too. :wtf:

The pots are about 2 gallons/7litre and 10"x10". I don't think they are root bound, they were re-potted a week ago. Plus I noticed from the last root-binding experience that they seem to get pretty droopy at night when they are running out of root room and they're not really doing that right now. (the re-potting "fixed" that) I was going to put them in larger pots when I put them to flower in a couple weeks. I am running out of room and have to do it soon. I never expected to have 5 plants. (I put in 4 seeds and this is what I got)

Bloody frustrating figuring out what these plants want. For a "weed" MJ sure is picky.

[Weedhound]

So you do check your soil runoff? Good for you! Is it usually at the edge? If so and you are sure they aren't rootbound then my vote would be for ph lockout. I aim for a runoff of about 6.5-ish.....right in the middle.

[stinkyattic]

Looks like K def/lockout.
I'd pot-up to the next size (do a heavy watering with plain water and let dry slightly first) and maintain your soil pH right at 6.7- water with whatever pH fert solution gives 6.7 runoff.

[PlainJane]

Thank you for the responses.

K def? Bloody hell, it is hard to tell what they want sometimes, isn't it?

I gave them a good watering today at 6.6-6.7 pH and the run-off was right near there (6.7-6.8). Next watering is supposed to be their nute watering. Since they don't look nute-burned I'm not worried about doing that, but it is disconcerting to see something not quite right with them and being unclear on what that is.

Weedhound: I water them in the bathtub and collect the runoff from their trays and dump it before I put them back in the cabinet. No wet feet for my kids.

I was shocked to see that there are already roots poking out the bottom of the drain holes. Whoever said HPS was not as efficient at promoting root growth had to be kidding. I will be potting them up next week or perhaps even this weekend because I am running out of room and need to flower them very soon.

Giving nutes with a re-potting is OK I presume? Also, if I understand correctly it is better to have them in their larger pots for about a week before putting them on 12/12, correct?

[stinkyattic]

Giving nutes with a re-potting is OK I presume? Also, if I understand correctly it is better to have them in their larger pots for about a week before putting them on 12/12, correct?

Yup, that is just fine. I'd do it mixed a little weak. And many people I talk to swear by letting the plants adjust from a re-pot before flowering. I think there is merit to that school of thought; I don't worry about it personally but yes, it is a good idea.

[polishpollack]

You're right about the over-fert and Mg deficiency. The golden yellow spotting you see in between the leaf veins is Mg deficiency. You're also getting some leaf tip yellow and brown colors, indicating fert burn. So... looks like you're ferting with too much nitrogen and not enough Magnesium. For Mg, you can just use about a teaspoon of epsom salts in a gallon of water and water them with that. The plants look like there getting too big for their pots. It should be understood that a root-bound condition can kill leaves too, but exact appearance of leaves when this happens is unknown to me as I've never seen these plants in a root bound condition.
You might consider getting a more balanced fert other that 8-2-6. Also remember that your soil might come with fertilizer mixed in and if so, then adding more fert to a small plant might be too much. On your water pH, remember to shoot for a pH that is both water and any ferts mixed together. If you lower pH then add fertilizer, you have to check the pH again to see if it is where you want it. Chances are you can avoid using the phosphoric acid.