Yellowing on the edges

I’m growing OG Kush autos in potting mix under led’s. This one is about 3 weeks old and last week I noticed a slight yellowing along the edges of the leaves. Under the led it looks much worse and yellow but in normal light it’s not so bad. The soil ph is about 6.9-7.0 and I’ve just been using demineralised water at 6.0 ph. I’ve used a seaweed foiliare spray once a week. Any help would appreciated. The original 2 cotyledons seem to be shrivelling up. I have some chicken manure, flora grow trio and cal mag I was saving till after the transfer but I haven’t used any of them yet.

Two things pop up is if you are in soil you should be around 6.3-6.8 so you are a little high. Also it is possible root bound in that pot and time to transplant.

It’s in a 500ml pot.

How should I get the ph in the soil down if it’s at 6.9-7.0 (soil) ?.

Should I try ph down in the water so it’s below the 6.0 that demineralised water comes at?.

I have larger pots and soil ready for the transfer. When you transfer do you put the manure mixed into the soil or just a small layer on top to seep down?.

I always mix amendments into soil and let sit for a while. And yea you need that pH to come on down a bit

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What’s the best way to bring the ph down?

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I would STRONGLY suggest using a soil product designed for cannabis like Fox Farms Ocean Forest and don’t add anything until flower. Be careful of over watering as well. My guess is a lockout of some nutes and an over abundance of others.

@raustin is great at diagnosis. See what she thinks.

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Thanks for the tag, @Myfriendis410.

This looks like a magnesium deficiency. You need to start adding nutes since your cotyldons have died off. You can add some Cal Mag, or Epsom salt to fix this problem.


I think it would be better to get the lockout dealt with which is likely magnesium. I was also worried about the moisture content of the soil in the picture. If the OP is in incorrect soil like MG then it would be counter to adding anything until the PH is sorted. That’s my thinking. @raustin

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Absolutely! You’ve got to have the Ph in check, otherwise adding anything will only make the problem worse. I think I was being lazy by not reading far up enough, sorry.


It’s Sunday. Thank goodness we’re not Jeb today haha! That’s WORK!

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That’s true. Lol

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Do you guys mean a full transplant to new soil?

Also appreciate all the help :grinning:

@Myfriendis410 do you mean too much moisture in the soil?

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You do want to go through a complete wet to dry cycle when watering. Stay away from “moisture control” or “needs no fertilizer for 3 months” soils. (Think Miracle Gro). I referenced the FF soil as a good choice although there are others too: any good organic potting soil will do, but the nice thing about Fox Farms is it’s buffered for cannabis’s preferred PH range.

And yes: you are likely root bound now and it’s time to transplant. Most of us are using fabric pots: cheap and unbreakable as well as much better for aeration of the soil. Remember; the larger the pot; the larger the plant. The larger the plant; the more bud mass. I have a friend who went from 3 to 7 gallon for autos when the general consensus is it’s a waste of time. He found out differently.

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@Myfriendis410 I’m in Australia and everything to do with weed and weed related products are harder to get with much less variety that in the U.S. or Canada. I can’t get that fox farms soil. The one I have is testing at 6.9-7.0. I was going to mix some dolomite lime and chicken manure to try to get the desired ph.
What is the desired ph for soil 6.5?

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Yes: 6.3 to 6.8. Dolomite lime is a good idea but I’d ditch the chicken guano unless it’s well composted and use sparingly.

If you want to PH your water lower to help that’s fine but don’t go past minimum soil values (6.2 or so)

@Myfriendis410 does lime raise or lower ph?

As for the chicken :poop:, I’m not sure how old it is but it’s ph is 6.5

When you’re adding nutes like flora grow trio, I noticed last grow it dropped the ph of the liquid very low. Do I bring that back up to 6.2?

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It’s liquid Sulfur to bring it down it says, does that look right?

Stick with the dolomite lime. It’s a buffer as well. You’re close enough to correct range I wouldn’t worry about sulfur. A small amount of composted chicken guano is good but be sparing. It’s easier to add nutes than subtract them.

@Niala, OP is in Australia with limited (read stealth) access to soils and amendments. He’d like to bring PH down around half a point and when transplanting would like to use chicken guano which is at PH 6.5. Any thoughts?

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