Do i need cal mag?

[420charlie]

Thank you for the information. I always check my ph before feeding and i run right around 6 on the ph. This is my first true grow, and everything im using is new to me. I waited almost 3 days to water and i only did cause the plant itself looked like it was starving for nutes. My humidity was higher but i started using a dehumidifier cause it seemed to high but its off now. I was worried i was gonna kill them when i was letting them dry up cause they looked awful so i got worried and fed them. I feel like i need to let them dry up but im worried about killing them

I feel you on so many levels, seeing the yellowing, splotching, on my leaves led me to believe I was starving them. If you’re feeding them and at a ph of 6 they should be able to uptake whatever is available. However if there is root damage, they’re going to be unable to perform their job. The plant will be working overtime to develop fresh roots. Peat retains a lot of water!

 

[Smoking Gun]

It is important to remember basic middle school biology, a cell is always looking for equilibrium. So, if the relative humidity of the air around your plant is only at 35% then the plants will only take up enough water to keep their cells at equilibrium with the environment around them. What this means is that if the RH of our air is low then the plants will not try to take up much water and will leave the medium wet for too long. By raising the RH of our air it will force the plant to take up more water to keep their cells at an equilibrium with the environment around the plants.

Another very basic piece of growing that surprisingly is often over-looked is that the plants roots want to be surrounded by oxygen and if the soil is constantly wet it cannot hold oxygen and you will suffocate the plant roots. In growing a little less is almost always better than a bit more. It is easy enough to add a bit extra but we cannot truly take out when we apply too much of anything.

 

[Smoking Gun]

If you’re feeding them and at a ph of 6 they should be able to uptake whatever is available.

Sorry, this is not true, for so many reasons. If the starting pH was low in the medium then applying food at pH 6.0 will not bring the soil pH up enough to make many nutrients available. Even if the pH of the medium is balanced for where plants will be happy, 6.0 is often too low in peat based mediums and will force the pH down once again creating issues with nutrient uptake. So providing nutrient mixes that are pH balanced properly is important.

 

[420charlie]

Sorry, this is not true, for so many reasons. If the starting pH was low in the medium then applying food at pH 6.0 will not bring the soil pH up enough to make many nutrients available. Even if the pH of the medium is balanced for where plants will be happy, 6.0 is often too low in peat based mediums and will force the pH down once again creating issues with nutrient uptake. So providing nutrient mixes that are pH balanced properly is important.

I didn’t think of the medium already being at a low PH, what PH should be fed to peat based mediums? I figured about 6 would be good, is closer to neutral better in peat based mediums?

 

[MIGrampaUSA]

I didn’t think of the medium already being at a low PH, what PH should be fed to peat based mediums? I figured about 6 would be good, is closer to neutral better in peat based mediums?

Smoking Gun is right. It's best practice to have your soil around 6.5 +3/-2 in pH. Peat is acidic and in it's natural unbuffered state, it can be in the 4.5 ph range. It's never a good idea to try to use your water to adjust soil pH. You're likely to do more harm than good in trying to correct it that way.

Think of how things are in nature. Most water in it's natural state is going to have essentially a neutral pH usually around 7.0 +/- some. Even pH 8.0 is considered for the most part "basically neutral".

PH lock-outs frequently occur when you're trying to use your water to correct poor soil pH. It can become a revolving door of issues. Set it up right in the beginning and things become much more manageable.

 

[420charlie]

Smoking Gun is right. It's best practice to have your soil around 6.5 +3/-2 in pH. Peat is acidic and in it's natural unbuffered state, it can be in the 4.5 ph range. It's never a good idea to try to use your water to adjust soil pH. You're likely to do more harm than good in trying to correct it that way.

Think of how things are in nature. Most water in it's natural state is going to have essentially a neutral pH usually around 7.0 +/- some. Even pH 8.0 is considered for the most part "basically neutral".

PH lock-outs frequently occur when you're trying to use your water to correct poor soil pH. It can become a revolving door of issues. Set it up right in the beginning and things become much more manageable.

I didn’t know that about peat! I’m growing in coco, and with it coming at a more reasonable PH naturally I didn’t think about that at all, my bad. Always learning, thanks!

 

[MIGrampaUSA]

I didn’t know that about peat! I’m growing in coco, and with it coming at a more reasonable PH naturally I didn’t think about that at all, my bad. Always learning, thanks!

I forgot to mention that your soil buffers the water and not the other way around. That's part of the reason that trying to use water pH to adjust your medium can be like chasing your tail.

I don't know much about coco but I assume the same principle applies. Now it's my turn to learn ... I thought coco was inert and didn't affect water pH? I'd like to know for sure.

 

[420charlie]

I forgot to mention that your soil buffers the water and not the other way around. That's part of the reason that trying to use water pH to adjust your medium can be like chasing your tail.

I don't know much about coco but I assume the same principle applies. Now it's my turn to learn ... I thought coco was inert and didn't affect water pH? I'd like to know for sure.

From what I’ve read Coco has a natural PH of 6.5-7.0 making it ideal as a medium. If you get your coco in a brick you can prep it with 6.0 ph and it’ll usually stay right around there. I’ve read it can buffer but it’s not very extreme. I’ve watered at roughly 6 and had run-off measure exactly the same.

 

[MIGrampaUSA]

From what I’ve read Coco has a natural PH of 6.5-7.0 making it ideal as a medium. If you get your coco in a brick you can prep it with 6.0 ph and it’ll usually stay right around there. I’ve read it can buffer but it’s not very extreme. I’ve watered at roughly 6 and had run-off measure exactly the same.

Good to know. I'm currently growing in soil but I have a 12 bucket ebb and grow style hydro system. That eventually I'll be using. I was going to use expanded clay pellets. But coco might be another option for me to explore.

 

[Smoking Gun]

This is a quick guide to nutrient availability in soil based upon pH.

http://www.avocadosource.com/tools/fertcalc_files/pH_file/pH.jpg

Good to know. I'm currently growing in soil but I have a 12 bucket ebb and grow style hydro system. That eventually I'll be using. I was going to use expanded clay pellets. But coco might be another option for me to explore.

If you are going to use the ebb and flow system I would highly recommend using the clay pebbles in the buckets. The flooding from the bottom may push the coco up and possibly out the top of the pot, at least that would be my concern; but I don't know for a fact that will occur. I do also like the high availability of O2 when using the clay pebbles in the buckets.

And to address your question about coco and if its inert, it is not and it will effect the pH of your water. Right out of the bag the coco may in fact be holding onto excess salts, which do flush out rather easily. However potassium is typically high in coco, thus most coco specific nutrients lower the amount of potassium in their mixtures. Coco also tends to be a sponge for calcium, which can get locked up into the coco where it is difficult for the plants to access it. Therefore typically additional calcium is needed when growing in coco.

Part of what makes this all occur as it does is the cation exchange capacity (CEC), which is relatively low. This means that coco can hold onto most nutrients until something else comes along to take its place. So nutrients always have to be applied when watering coco otherwise the plants go hungry rather fast. This is also the mechanism the ultimately accounts for our pH necessities in coco.

 

[MIGrampaUSA]

This is a quick guide to nutrient availability in soil based upon pH.

http://www.avocadosource.com/tools/fertcalc_files/pH_file/pH.jpg


If you are going to use the ebb and flow system I would highly recommend using the clay pebbles in the buckets. The flooding from the bottom may push the coco up and possibly out the top of the pot, at least that would be my concern; but I don't know for a fact that will occur. I do also like the high availability of O2 when using the clay pebbles in the buckets.

And to address your question about coco and if its inert, it is not and it will effect the pH of your water. Right out of the bag the coco may in fact be holding onto excess salts, which do flush out rather easily. However potassium is typically high in coco, thus most coco specific nutrients lower the amount of potassium in their mixtures. Coco also tends to be a sponge for calcium, which can get locked up into the coco where it is difficult for the plants to access it. Therefore typically additional calcium is needed when growing in coco.

Part of what makes this all occur as it does is the cation exchange capacity (CEC), which is relatively low. This means that coco can hold onto most nutrients until something else comes along to take its place. So nutrients always have to be applied when watering coco otherwise the plants go hungry rather fast. This is also the mechanism the ultimately accounts for our pH necessities in coco.

Thank you for that. Very good information ... I already have several bags of the clay pellets. I'll stick with my original plans.