FF Growbig and Yellow leaves

[clay10]

Hi all. long time reader first time poster.

I'm on my second round grow from clones on the first round.

So i started using FF Grow big and it seemed to really boost my vegging plants. This is one of my first mother's and she's been pretty resilient so far. I watered her this past weeked ( 6 days ago), and as usual the tops greened up a little bit. That was probably her fifth dose of FF nutes. However today,
I came out and all the older leaves are yellowed pretty bad. I really couldnt understad a Nitrogen deficiency as I just fed her a few days ago, which she was 95% green before I fed. Also, some are getting brownish dead spots as they wither away.

On a different note, after just recently buying a pH meter, Ive had been watering with 8.0 pH tap water, but the FF had corrected it pretty close anyway. I DID screw up my flowering set, but thats a whole nother story.


I blame a few of my difficulties on bagseed randomness. But i figure if I can learn to grow shitty genetics, I can get some good stuff when I finally get around to ordering seeds.


Grow Details:

Vegging under a 175W Metal Halide

Soil: 50% Perlite, 50% Calloways premium potting soil (from a local gardening shop, worked well for a while now, its not nutes or anything)
Its pretty airy, but I like it and I check everyday so i rarely have water issues
temps: 80-85 ( i know its high, but they,ve never really had trouble before, and they get continous fresh air flow from outside the cabinent )
Ferts: i tsp per gallon FoxFarm Grow Big, once a week.
ppM: about 600
pH : 6.5ish


and pics






whatcha think? Thanks!

 

[Brian1975]

If PH is fine, I would guess Mg deficiency.

Margins of the leaves are turned up, and the tips may be twisted. Leaves are yellowing (and may turn brown), but the veins remain somewhat green. >> Magnesium (Mg) deficiency.

Mg-deficiency is pretty common since marijuana uses lots of it and many fertilizers don't have enough of it. Mg-deficiency is easily fixed with ¼ teaspoon/gallon of Epsom salts

1/4 tsp. to half a tsp. twice throughout the grow is all that I supplement.

 

[Guest]

Looks to be a mag def to me also.

 

[clay10]

should I foliar feed to get a quick dose?

 

[Brian1975]

You could, I guess, if its not watering time. I would just add epsom to my next watering; up to you though. I avoid spraying anything on the plants if I can.

 

[MTF-Sandman]

Yeah, just add some epsom salts or cal mag the next watering...I've never been a fan of foliar spraying - especially on damaged leaves that can't uptake the nutes nearly as effectively as roots.

FWIW - That purpling between the veins (middle pic) is classic of a more severe mag def.

 

[Blackmelo]

hi clay,
The Epsom salt will definetely help but you want to be feeding a bit more nitrogen too imo.

I had a look at the ratio of NPK of growbig and it does not really sound right. As far as I can tell its 3-2-6, wheras you really want to be feeding most N out of those 3 main nutes. I would try and ammend this by either adding some Nitrogen available from nirvana the seed seller or some liquid seaweed which is high in N.

ps: instead of feeding 1 tablspoon per gallon once a week, try feeding 1 teaspoon on every watering. The plants will prefer a more consistent and constant feeding to an more erratic one.

 

[clay10]

Wow, quick reponses. Thanks.

Looking at this FF grow big bottle, I've got the soil flavor. the hydroponic is the 3-2-6.

I guess I assumed they should be getting enough N and Mg.

Off the back of the bottle:
(Its a 6-4-4)

TOTAL NITROGEN:.....6.0%
2.9%...ammoniacal Nitrogen
3.1%...Nitrate Nitrogen
AVAILABLE PHOSPHATE .....4.0%
SOLUABLE POTASH.....4.0%
Magnesium................. 0.60%
Boron 0.02%
Copper 0.05%
Iron 0.10%
Manganese 0.05%
Molybdenum 0.0009%
Zinc .05%
Chelated Zinc .05%

 

[Blackmelo]

hi clay, you might be interested in this site here http://www.angelfire.com/cantina/fourtwenty/articles/profiles.htm

I roughly worked out how much your nutrient contains and how much you are feeding your plants and it seems 1 teaspoon per gallon of grow big is a good amount. Feed that on every watering from now.
Your nutrient contains too little magnesium which we already suspected so get some epsom salt. I would recommend half a teaspoon per gallon in vegg and 1 teaspoon per gallon in flowering.

Ps: since they are already quite yellow you can try up to 2 teaspoons of grow big and up to 2 tespoons of epsom salt on evry watering till they green up. That is the max I would recommend and it should perk them up quicker.

 

[chimmer]

can you just mix epsom salt into the soil before planting. i am using ff also.and when i can not get to the hydro store.i buy dirt at walmart(sad aint it) and i have no prob with ff nute. but this last time i got mericle grow moisture control. and i am having the same prob.i feed 1 teaspoon per gal every watering. they go along fine and about week 3 they start yellowing on bigger leaves brown spots leaves tips curel up then go crisp. but the new growth is green. i have been watering when they get light. but this dirt has coco in it .so i started watering more every other day for a 3 gallon pot till alot of water ran out. this has helped. but i also added about a tablespoon per pot of epsom slat. did the e-salt in the soil do anything.

 

[Pimp Aurora]

Yeah, just add some epsom salts or cal mag the next watering...I've never been a fan of foliar spraying - especially on damaged leaves that can't uptake the nutes nearly as effectively as roots.

FWIW - That purpling between the veins (middle pic) is classic of a more severe mag def.

like this?

thats one of mine

no worrys though, they got a good drink of epsom salts and grow nutes and i'll try and remember this for next time

 

[clay10]

I fed them just a tsp of epsom salt mid week, and it the yellowing has seemed to slow if not stop. I am resuming regular feeding schedule today (tsp FF grow big weekly) and hopefully everything will be back in swing. Next weekend I'll give them an extra hit of N with a little fish emulsion to see if they like it.

Thank you everyone for the speedy solution and help. I can tell Ill be posting quite a bit more as I learn WTF im doing.