Help fixing soil PH

Hello everybody!

I'd been having problems with my plants since practically the sprout of my seedlings (stunt grow, yellow lower leaves, little dark spots on some leaves), and after trying multiple solutions I found that the issue is the PH of my organic soil, which is at 7.6. Right now my plants are growing in small containers, waiting for transplant, but I already have a soil mix that has the same PH value and I don't want to throw it away.

Is there a way to LOWER the PH of my soil mix? Should I throw it away and buy a new one?

I've read that ferrous sulphate or aluminium sulfate could help me fixing this, but I can't find a reliable source to calculate the exact amount...

I don't want to spend more money! But right now I'm losing my garden and have lost precious amounts of time!

I think the problem is that I added dolomite lime to my soil mix...

Thanks in advance!!!

how did you determine your soils ph? where do you get your water from?

How are you taking the pH of your soil? How much dolomite lime did you add?

I doubt your problems are stemming from the pH of your soil

If it has lime in it you will not be able to change its ph and adding stuff that does will only increase your problems.

It is rare to have an alkaline soil and i would also ask how you know its ph as well?

Dont listen to a lot of the fallacies about soil, UB, fatman, oldtimer1, stitch and a few others have written some great threads on soil if you can find them on google search, they cover everything from ph to flushing

Jose Maria Urdaneta said:

Hello everybody!

I'd been having problems with my plants since practically the sprout of my seedlings (stunt grow, yellow lower leaves, little dark spots on some leaves), and after trying multiple solutions I found that the issue is the PH of my organic soil, which is at 7.6. Right now my plants are growing in small containers, waiting for transplant, but I already have a soil mix that has the same PH value and I don't want to throw it away.

Is there a way to LOWER the PH of my soil mix? Should I throw it away and buy a new one?

I've read that ferrous sulphate or aluminium sulfate could help me fixing this, but I can't find a reliable source to calculate the exact amount...

I don't want to spend more money! But right now I'm losing my garden and have lost precious amounts of time!

I think the problem is that I added dolomite lime to my soil mix...

Thanks in advance!!!

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7.6 is a little too high. A soil having a ph of 7.0 means the cation exchange sites are 100% full. Full of what, depends on what you use..

Being you used dolomite lime, Your cation exchange sites are overloaded with calcium and definitely magnesium,probably locking out potassium.

These are minerals/heavy metals that stick in your soil and can only be taken out by plant absorption. They can also be leached out over time given your medium has a low CEC..

If I were you I'd take the seedling(s) out of the soil and put them in Solo cups. Break up your soil and mix it with straight peat. I'd add 2.5 gallons of peat to every cubic foot of soil, give it a few days and check your ph, should be within range. If not, keep adding peat until you get it adjusted to your liking..

Replant seedlings and they'll take right off.

chuck estevez said:

how did you determine your soils ph? where do you get your water from?

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I took 1 cup of soil and 1 cup of water with a ph of 7, mixed it and let it sit for about 3 hours. Then I filtered the water and took the ph measure with ph meter pen. The result was 7.6. I found that same "recipe" in a lot of different websites so I thought it was ok.

Is it a good method? I don't have a ph meter for soil so...

The problem is that I've tried everything else, and the only thing that still fits is chlorosis due to a elevated ph in soil or water. The soil was a mix I made and I'm pretty sure it has everything the plants need, but it seems that they can't get the nutes from it. And the only component in the soil that I can think of that has an elevated ph is dolomite lime... even though I only used half a cup for each cubic ft.

I'll post some pictures to confirm.

By the way. I wasn't measuring the ph of the water up until now. The water I was using registered 7.0. Now I'm watering with 6.0...

Soil mix:

2 parts soil mix from a garden center (The bag claimed that the ph was between 6.5-7.0)
1 part peat moss
1/2 part coco coir
1 part rice hulls (no perlite around here)
1 part humus
1 cup bone meal
1 cup granite rock dust
1/2 cup dolomite

MistaRasta said:

7.6 is a little too high. A soil having a ph of 7.0 means the cation exchange sites are 100% full. Full of what, depends on what you use..

Being you used dolomite lime, Your cation exchange sites are overloaded with calcium and definitely magnesium,probably locking out potassium.

These are minerals/heavy metals that stick in your soil and can only be taken out by plant absorption. They can also be leached out over time given your medium has a low CEC..

If I were you I'd take the seedling(s) out of the soil and put them in Solo cups. Break up your soil and mix it with straight peat. I'd add 2.5 gallons of peat to every cubic foot of soil, give it a few days and check your ph, should be within range. If not, keep adding peat until you get it adjusted to your liking..

Replant seedlings and they'll take right off.

Click to expand...

I'll try what you suggest if I can confirm that the ph seems to be the problem.

have yourself some moist soil, stick in your ph pen. let it sit for 10min and you'll have a good reading of your soil ph.
don't base yourself on runoff water. it's the soil ph you want.
you can try lowering it with plain white vinegar.
but if you are using dolomite lime you'll have a realy hard time countering the alkaline properties of it. especialy if it's rich in your soil

anyway, your plants are still small in size, get some better dirt and repot asap

Best find you some perlite. Your problems aren't coming from the dolomite, especially not at 1/2 cup/cf, but a lack of aeration and a too dense mix. Bet those containers stay wet forever.

That bagged soil may be ok, maybe not. IDK I always make from scratch. But rice hulls aren't all that for aeration, turning to mush in fairly short order. Someone will have perlite, search better, but get that mix lightened up!

Wet

Jose Maria Urdaneta said:

I'll try what you suggest if I can confirm that the ph seems to be the problem.

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Ph doesn't matter to a degree in organics..Sure, if I have a big pot with lots of biology and lots of room for said biology to alter things over time, to eventually buffer them as we have in nature, then yes, ph doesn't matter.

Too bad nature doesn't grow fields of veggies..

we're talking about mineral exchange in a pot, it's completely different and every variable needs to be accounted for to make sure proper exchange is happening.

If you had this plant in a big pot I'd be willing to say ph doesn't matter but being in that tiny little cup nothing is going to change.

You can change the ph of your water all you'd like but this is the reason for CEC, to hold buffering minerals and keep them there. The ph isn't going to change until those mineral ratios change.

are you using DISTILLED water?

Wetdog said:

Best find you some perlite. Your problems aren't coming from the dolomite, especially not at 1/2 cup/cf,

Wet

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I've always had problems with lime and it makes sense considering how much magnesium is in lime in comparison to calcium.

Why not just use calcium carbonate as a buffer?

I've seen read a lot of comments talking about using Dolomite lime. Dolomite really is a six month fix, as that is how long it takes to really be effective as it breaks down slowly. What you really need in hydrated lime, as it breaks down immediately, which is what you need for an average 3 month grow. It will neutralize the soil PH to 7.0, and then you can adjust further by lowering your feed solution to 6.3/6.5 which is the sweet spot for marijuana. I noticed that you have used mulch for a top dressing, which will fuck with your PH also. It will send your PH up big time every time you water through it it. Loose the mulch, and some hydrated lime in a small amount (1 tbs to gallon of soil), and you should be fine. Oh, and also you will read that organic soil doesn't need adjustment, which is true for soil with active micro organisms, but that requires developed soil, like for six months to set up colonies of the bacteria, which really ain't happening in 3 months, without some serious teas. Good luck

Wetdog said:

Your problems aren't coming from the dolomite, especially not at 1/2 cup/cf, but a lack of aeration and a too dense mix

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The dirt is nicely aerated, and it drains and drys fast.

Jimdamick said:

I noticed that you have used mulch for a top dressing, which will fuck with your PH also. It will send your PH up big time every time you water through it it. Loose the mulch, and some hydrated lime in a small amount (1 tbs to gallon of soil), and you should be fine.

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The thing is that mulch, or rice hulls, is my aeration amendment, so the whole mix is full of it. I didn't know that it can fuck up with the ph of the soil, and now that I think it better, the source I get it from wasn't the most clean or reliable, and the hulls were full of hubris. In the other hand, everybody use that as an aeration amendment here, and they're doing fine as far as I know...
Do you think that mixing the hydrated lime in the proportions you say can save my soil mix? Would it be better to start a new mix from scratch?

MistaRasta said:

If you had this plant in a big pot I'd be willing to say ph doesn't matter but being in that tiny little cup nothing is going to change.

You can change the ph of your water all you'd like but this is the reason for CEC, to hold buffering minerals and keep them there. The ph isn't going to change until those mineral ratios change.

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So do you think that if I transplant them to bigger pots with the same soil they will get better?

Thanks for the help everybody!

MistaRasta said:

I've always had problems with lime and it makes sense considering how much magnesium is in lime in comparison to calcium.

Why not just use calcium carbonate as a buffer?

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I do, mostly on reamends, calcitic lime. Don't bother with oyster shell flour due to shipping and calcitic lime is a 1 to 1 equivalent, being pure CaCo3. Then again, calcitic lime just doesn't sound as cool as oyster shell flour so many will spring for shipping rocks.

IME that whole Ca/Mg ratio stuff just doesn't hold up for container grows with peat based mixes. In my soil gardens I watch for it and deal with it. But with container mixes it just has never been a problem, stuff leaches out over time. In my mostly red clay soil it never leaches out.

OP ... I'd look real hard at those rice hulls. No, not everyone uses them and most just use them once and learn. Larger pots will help, organics just don't do as well in smaller containers, but find a local source for perlite. Being totally inert it has zero effect on pH.

Do NOT mess with hydrated lime, at least till you have a few years experience.

Wet

Wetdog said:

I do, mostly on reamends, calcitic lime. Don't bother with oyster shell flour due to shipping and calcitic lime is a 1 to 1 equivalent, being pure CaCo3. Then again, calcitic lime just doesn't sound as cool as oyster shell flour so many will spring for shipping rocks.

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Calicitic lime is great! If I couldn't get oyster shell flour locally I'd use this, or some aragonite or zeolite.

Wetdog said:

IME that whole Ca/Mg ratio stuff just doesn't hold up for container grows with peat based mixes. In my soil gardens I watch for it and deal with it. But with container mixes it just has never been a problem, stuff leaches out over time. In my mostly red clay soil it never leaches out.

Wet

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Everyone's mix is different. From the compost put in to the aeration put in, all factors have to be attributed and thus gives everyone different result. In otherwords If it works, it works!

Jose Maria Urdaneta said:

So do you think that if I transplant them to bigger pots with the same soil they will get better?

Thanks for the help everybody!

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Not necessarily, I was saying, if you made your volume of soil larger you'd have more room for organic matter to buffer everything and balance it all out, which will take time.

Being as you already mixed your soil and you're at where youre at id recommend just adding some more peat and aeration to your mix. This will neutralize your mix in a matter of days and is the easiest solution.

Not to mention, you noted putting 1 cup of bone meal in as well, I'm not sure about your ratios but it seems as though you probably have too much phosphorus as well, which the peat will take care of.

I have a super soil that I got from buildasoil.com said to use rice hulls and i am having ph issues as well 8+ should i add peat? I'm in flower and having issues. I just flushed and was going to water with 5.5 phed water. Will this help? What else can i do?

Wetdog said:

I

IME that whole Ca/Mg ratio stuff just doesn't hold up for container grows with peat based mixes. In my soil gardens I watch for it and deal with it. But with container mixes it just has never been a problem, stuff leaches out over time. In my mostly red clay soil it never leaches out.



Wet

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Explain me more please

http://buildasoil.com/products/the-clackamas-kit
This is my soil mix I used rice hulls for airation. I checked my water run of at 8 + but i just got a new soil meter and I'm at 6.5 which is good but showing major phosphorus deficiencys. I use modularhydro buckets which is similar to dwc but with soil. I flushed my plants today will see what happens i guess