Possible Magnesium Deficiency?

My 2-3 month old clones are experiencing yellowing of new growth. The yellowing is localized on the perimeter of the leaf, leaving an arrowhead-shaped darker, healthier green in the center of the leaf. Researching google, I diagnosed this as a magnesium deficiency (whether I was right or wrong) and followed the directions posted under the sticky "epsom salts = not miracle cure)," spraying the leaves (yesterday and today). The condition seems to have become worse since applying epsom salts. My guess is that when I flushed my plants a week ago, I leeched out one or more micronutrients, just can't figure out which one(s). In addition, the newest growth is very light greenish/yellowish and looks "blotted." I will post pictures later tonight, just wanted to get this up ASAP...any ideas??

Here are the specifics:

Grow Medium = Scotts Topsoil (contains peat) + Vermiculite (80%/20%)
Location = Indoors
Nutrients = Miracle Grow All Purpose (1/8 tsp/gal)  (this is ¼ recommended dose)
Rate of application = Water â?? Feed â?? Feed (then repeat). Plant was flushed with water quantity equivalent to pot size once a week ago
Runoff pH = 6.2
Water source = Tap Water is pHâ??d from alkaline to 6.5
Age of plant = 2-3 months
Lighting source and distance from plant = T5/55W/10,000 Lum/6400K/ Within 6â?� above canopy.
Air temperature = Daytime 80 deg. Nighttime 75 deg.
Air % Relative humidity = roughly 50%
Lighting schedule = 18/6
Type of ventilation = 4â?� inline fan (170 cfm) + 12â?� regular (circulatory) room fan
Did NOT pre-soak media in pH corrected solution

waiting to see pictures.

-shake

Camera broke :( but i bought a new one..should be here in 3 days. I'll post the pics ASAP!!

There should be enough Mg in tap water to not have a deficiency. Conversely, if you use reverse osmosis, you should add some Cal/Mg.

You might also be root bound and need repotting.

I use tap water, perhaps there isn't enough Mg in it? Also, I re-potted from 1 gal to 3 gal only 1 week ago, still think it could be root-bound?

Topsoil is usually buffered to a lower ph, (6.0 or so) so I'd contact Scotts, and see what their Topsoil is buffered to.

Miracle Grow All Purpose directions are for a 10 to 14 day period. (1 tsp per gallon) Half strength (a weekly dose) would be approx 1/2 tsp per gallon. When I use it, I use 1/4 tsp per gallon, twice a week.

6.5 ph ingoing is a tad low before adding nutrients. Try bumping it up to 6.8 or 6.9ish before nutes. 6.5 ph is fine for plain waterings, though.

Too young for a true calcium or magnesium def. But unsulfured molasses at 1/4 tsp per gallon, once a week usually doesn't hurt, but is mostly unnecessary. In mid to late flower, I give 1 tsp per gallon, once a week.

Rusty, I called Scotts and they could only tell me that the soil is pH'd to a range of 5.5-7.5. I'll pH-UP my nutrient solution slightly and use Miracle Grow as you suggested.

I should add that the problem has progressed throughout the entire plant (all nodes). New growth is lighter green. I'm going to continue using the Epsom/dish soap foliar spray daily on affected leaves. Liquid Karma is arriving tomorrow; I'm going to see if that will help too.

Shake, I promise to get those pics up ASAP. Do you have any suggestions in the meantime?

All of your help is appreciated, thank you!
-purp

Quote:

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Originally Posted by purpleskunk777

Shake, I promise to get those pics up ASAP. Do you have any suggestions in the meantime?

All of your help is appreciated, thank you!
-purp

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i'd like to reserve my opinion before adding anything. apparently i don't know what the fuck i'm talking about. lol.

it sounds like magnesium from the description. again, just my opinion until we get pics/more info.


-shake

Quote:

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Originally Posted by headshake

apparently i don't know what the fuck i'm talking about. lol.

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Oh, please. Who would say such a thing ;)


I think I found the problem :D
So I did a runoff once again. ph = 7 going in, 6 out the other end...judging from the chart posted in the sticky of the plant problems forum, P, Ca, and Mg would all be locked out at this pH (less than 6). I flushed with over 3X pot size (12 gal) to a runoff of about 6.7 we'll see how things go I'll keep y'all posted!

From what I understand, that buffering range is refering to the wide range of products, not their ph range for the Topsoil itself. Indoor mixes are usually buffered to an approximately neutral ph, (7.0ish) outdoor products (compost, mulch, topsoils) are buffered to a lower ph.

If your ingoing water is 7.0 ph, and your runoff really is 6.0 ph, then the Topsoil is likely buffered to 6.0ish ph. Flushing won't improve this, so I'm curious what you're using to determine your runoff ph? A color-coded test kit assumes you are using clear water. Any tinting of the water will skew the results.

You might want to look for an indoor mix that's properly buffered. Or, you can get some garden lime, limestone dust, or dolomitic limestone to buffer the Topsoil, and transplant asap. Practice on an empty pot of the topsoil, as different buffers need to be applied at different rates, and must be watered-in to prevent root burn. Topsoil is usually heavy in manure, which temnds to burn cannabis roots at those quantities. You need a ph pen for this process, though.

Did you check to see if you're rootbound like WW mentioned?

Today was very frustrating. I'm fairly new at this, and ive run into every possible problem you could think of. Oh well, some day this will all pay off but until then boo hoo :(
Rusty,
I am using a color-coded test kit and the water is pretty clear when i go to test it. I purchased some indoor potting soil (Scotts premium brand) and tried to pH it, but the runoff is too dirty to test with my pH kit. I decided to transplant into a larger container with this soil because if I don't do something quick, my plant will die.

Also, upon transplanting I found the plant was indeed root-bound.

This will be hit-or-miss, as I don't know the pH of the soil I transplanted into and I may have stressed my plant to the point of death. I watered with some liquid karma that I got today as well in hopes that it'll reduce stress of transplanting and my plant surviving.

Camera's arriving tomorrow ill have pics up asap.
Thanks again,
-purp

OK boys and girls, here are the pics as promised!

Since yesterday's transplant, the plant has not grown at all and appears to be in a similar condition as prior to the t/plant. I'm guessing this is a sign of stress and hoping that things will only get better from here.

Plant's a little droopy because of all the flushing I did before I realized the pH of the soil was buffered.

So I can learn from this, would you be able to tell me your opinions on whether this was caused by a Mg deficiency, rootbound, or the pH of soil being 6.0, or all the above??
Also, any suggestions on what to do besides wait and hope for the plant to recover from stress?

Much appreciated,
-purp

http://boards.cannabis.com/members/p...6-dscn0004.jpg

http://boards.cannabis.com/members/p...7-dscn0005.jpg

http://boards.cannabis.com/members/p...5-dscn0003.jpg

http://boards.cannabis.com/members/p...3-dscn0001.jpg

http://boards.cannabis.com/members/p...4-dscn0002.jpg

....what pictures? Are the links working for anyone else?

You can add pix to your posts with the 'attachment' paper clip.

Oops, here you go...

another quick question..any chance the rich green color will come back to the pale leaves??

-purp

Rootbound and ph issues.

Give her a few days to recover from the transplant and acclimate to their new surroundings. (the soil) She might get a little worse before she gets better. By next week you should see some color-up and possibly new growth if all is well.

Leaf color-up should be equal through the existing leaves. But, the yellowish leaf margins will green-up to the same proportions of the greener parts. In other words Greener, but still two tone. That isn't likely to change, but the new growth should be 'normal'. Hopefully.

Stay away from the desire to use nutrients for a few weeks. There's already timed release fertilizer in the potting mix.

Let us know....:thumbsup:

Sounds great :)
I'll refrain from nutrients and post some new pics up next week.
Thanks again for all your help!
-purp

Any resolution to your problem?

plant seems to be perking up nicely. i'll post pics in a couple days to show u the progress.

got any pics?

Sorry, I can't get the pics to post; tried resizing/re-formatting it and everything, still won't work! I've managed to get them up on my album though. Look at the first 3 pics in the album in my profile "Great White Kush." I took them 3 days ago.