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Magnesium Deficiency

Zenocide

Member
Hi fellow hobbyists

New to this and on my 2nd indoor grow, 1st grow I learned a great deal from and on this 2nd grow it shows which I am quiet pleased with although 2nd week into flower was hit with a Magnesium deficiency tips and stripes so I've flushed and gave a hit of calmag and it's regular feed which seems to have corrected the problem.

A week on and effected fan leaves seem to be getting better and the bad tips I chopped off haven't started dying any further. I would like to ask what caused the Mag deficiency as soil PH was within tolerance I'm guessing the soul just simply ran out of Mag?

Check out the pics please and thanks for any advise.

FuNYjpc

NWNC4Tm

FKfItSO
 

moses wellfleet

Well-known member
Moderator
Veteran
You need to provide as much info as possible, medium, environment, nutes etc.

Are you talking about organic soil?
 

Zenocide

Member
Hi moses, I'm no serious grower yet probably don't plan to be but the soil is some grow bag from my local nursery with perlite and it's in a 5ltr pot with good drainage and I belive cannabis is similar to basil so I got some 4-4-4 feed I give it when I water it, the lights are 4 26watt cfls and 2 25watt uvb 10/150 cfls I added when I put it in flower. Temps are between 75 - 85f and I have no idea on the humidity.
 

bigworm74

New member
you need to use bigger pots you are probably running all your nutrients out of your soil i would go at minimum of 3 gallons per plant which would be like 10 or 11 liters i think.
 

corky1968

Active member
Veteran
I recently purchased plain old Dolomitic Limestone at a garden section of a
large store. It's made up of mostly calcium carbonate & magnesium carbonate.

I also purchased a small bottle of Epsom salt (magnesium sulfate).

Epsom salts is really water soluble and will treat a magnesium
deficiency quicker than Dolomitic Limestone.

Having both for my plants is nice though.

Personally, I find lots of specially labelled nutrients at Hydro Stores are overpriced and marketing gimmicks.
 

PoweredByLove

Most Loved
that's not magnesium, that's a K def. prolly adding too much calcium.do you have high ppm's in your water out of the tap? you prolly don't need to add any more calcium, don't use calmag, use epsom salt to add only the magnesium.
 

Zenocide

Member
Thanks for the reply guys I think I will use a bigger pot on the next grow as suggested by bigworm74 as I think the plant is too big for this small pot I'm guessing it sucked all the nutes out of the soil fast (overlook by myself).

Thanks for the advise on the Epson Salts and Doloimte Lime corky1968 I will make sure to grab some Lime from the garden center the next time I'm there.

PoweredByHaters, I'm not sure on my mains supply ppm although I do water with 1/2 rain/mains mix as I read rain water doesn't contain certain trace elements that tap water has, I will be sure to pick up a meter to test my mains.

I'm curious on the K def as you suggested, is there a fast way to get some potassium into her?

Thanks again guys.
 

Granger2

Active member
Veteran
Looks to me like a bit much N [tip burn], along with needing Epsom. Cut back 25% on the 4-4-4. BTW, 4-4-4 is not a good formula for veg, nor bloom. Good luck. -granger
 

Zenocide

Member
Excellent now that gives me an excuse to finish off burning some wood I've been putting off for the past month.

I'll give the top of my soil a light dusting of ashes and see how she goes, Cheers!
 

corky1968

Active member
Veteran
BTW: Hardwoods are better for potassium than Softwoods.

Hardwood = maple and oak are the best.

Softwood = pine,cedar, spruce or other evergreens.

Don't use lots either. Just a fine dusting on the soil surface will do.
 

Zenocide

Member
Thanks Granger2

I thought too much N produces deep green clawed tips? Maybe I read that wrong somewhere. I do agree I need to got my NPK ratio better but 4-4-4 was all that was available that seemed pretty balanced so I chose that.

I do now know that more N is needed in Veg and P in bloom, I'm pretty limited to what nutes I can get at my garden center but do you have any recommendations for any off the shelf liquid nutes?

I also picked up a nice 60L bag of Jack's Magic pete compost with seaweed for my next grow which I read is pretty good. Probably not perfect but of well..
 

Chimera

Genetic Resource Management
Veteran
Do NOT put a bunch of wood ash on these plants, that is terrible advice and a sure way to make a decent looking plant turn horrible.

That plant is not K deficient. If you are using almost any type of fertilizer, K is almost never deficient.

If anything you might have a slight soil toxicity from over-fert. I suggest running an effluent test to determine pH and salt build-up in the soil.

Take pure water, pH'd to 7 and with a knownEC/ppm and run an equal volume of water to the amount of soil through the container, and catch he runoff. Then test the pH and EC/ppm of the runoff.

From there you can make some informed decisions.
 

corky1968

Active member
Veteran
Do NOT put a bunch of wood ash on these plants, that is terrible advice and a sure way to make a decent looking plant turn horrible.

I said a fine dusting like the way a person adds salt to pasta.
I didn't mean to use a shovelful.
 

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