New Grower New organic soil mix high PH

[M4A]

I recently mixed together an organic soil mix based on FullDuplex's mix but used mushroom compost instead of cow manure, and powdered oyster shells instead of egg shells. After mixing it all thoroughly I ended up with 2 5 gallon pails of the mix. I let it sit 5 days and did a PH check. If I mix equal parts of 6.5 water and my soil mix, my checker shows 7.8 which is way too high. If my math is right, my soil mix must almost at 9.

I don't have access to sulfur locally so I was considering cutting the mix with spagnum, but I have no idea how much I should be using, or how effectively it will work.

Does anyone have any experience dropping PH? I've only ever had to raise it prior to this mix

 

[M4A]

I did some checking and found that I can get garden sulfur at my local big box store, and I would prefer to use that over diluting my soil mix with spagnum if at all possible.

The mix had 1 cup of dolimite, 1 cup of oyster shells, 1 cup of epsom salt, and 1 cup of baby cereal all of which I'm certain raise the ph level quite a bit. Does anyone know how much sulfur I should be adding to 3cu ft. of this mix to get it back to 6.5?

 

[Muddy]

Sulfur is very slow acting and won't have an effect on the pH for quite awhile, at least 2 months and possibly longer. Aluminum sulfate is faster acting and will show effects in a few days. However, 5 days isn't long enough to wait to get an accurate reading. It's generally recommended that the soil be moistened and allowed to sit for at least a month for everything to combine and stabilize. For more accurate readings I would also suggest you invest in a Control Wizard Accurate 8 soil probe. You can find them on the internet for around $50. Well worth every penny.

 

[M4A]

Sulfur is very slow acting and won't have an effect on the pH for quite awhile, at least 2 months and possibly longer. Aluminum sulfate is faster acting and will show effects in a few days. However, 5 days isn't long enough to wait to get an accurate reading. It's generally recommended that the soil be moistened and allowed to sit for at least a month for everything to combine and stabilize. For more accurate readings I would also suggest you invest in a Control Wizard Accurate 8 soil probe. You can find them on the internet for around $50. Well worth every penny.

I've got seedlings that need to go into the mix in about a week, any suggestions as to what you would do?

 

[Muddy]

Aluminum sulfate might be your best option but I'm not convinced that your pH readings are accurate.

 

[M4A]

Aluminum sulfate might be your best option but I'm not convinced that your pH readings are accurate.

And you would be correct that they were not. I ordered a CWA8 and when it arrived stuck it into the soil and let it sit for 30 minutes and it seems to be reading around the 5.3 area, thank goodness I listened to you and picked up a good soil probe. Looks like a bit more dolomite is in order and all is good.

 

[Mr Piggy]

Five days for oyster shells and egg shells is nowhere near enough. You have to let is sit for about two months before it will stabilize. When you use the CWA8 the soil needs to be moist as well, otherwise you will not get an accurate reading.

also be aware that if you add a bunch of oyster shell and egg shell now, then up it with some fast acting product, you could well shoot over your mark in about seven or eight weeks when the rest breaks down.

 

[M4A]

Five days for oyster shells and egg shells is nowhere near enough. You have to let is sit for about two months before it will stabilize. When you use the CWA8 the soil needs to be moist as well, otherwise you will not get an accurate reading.

also be aware that if you add a bunch of oyster shell and egg shell now, then up it with some fast acting product, you could well shoot over your mark in about seven or eight weeks when the rest breaks down.

I keep my soil moist and in lidded containers so it was already damp when I used the probe. Stuck it into a container of recycled soil from my last grow and it showed a pH of 5.75.

I'm aware that pH changes over time as things break down and some things take longer than others to really enter the mix. By the end of my previous grows with a similar soil mix my runoff was in the very low 6's to midhigh 5s and the plants weren't growing to their fullest. After reading some of FullDuplex's posts about his soil mix I saw he was adding in powdered eggshell and Epsom salt which was missing from my mix and should in theory help raise the pH as well as add nutrients. Since he's able to use his mix as soon as next day and still growing monsters the pH must be in a range that doesn't cause lockout.

I was going to bump the pH up some with dolomite since its a fairly safe buffer to bring things closer to 6.5 without worrying about it going over 7.

 

[Muddy]

Glad to hear you made the investment in the Accurate 8. You're going to love it and it will make you a better grower. Great tool. 30 minutes is too long to get accurate readings with the Accurate 8. About 5 minutes is sufficient. Take 3 readings from different spots and average them.

 

[Mr Piggy]

It's good that you were looking at FD's formula, but here's the thing about soil mixes... it's an exact art. You can't just add a little here or there to suit your needs, it has to be balanced. If someone's soil mix works for them in a certain time frame, it's because of that EXACT formula. If you wing it and mix and match, you are not going to get the advertised results, period. It is a fact that the oyster and egg shell take about two months to break down and start working. Nothing is going to change that or speed it up. I definitely use dolomite in my mix, hell I'd even sprinkle it on my breakfast cereal if the wife wouldn't give me funny looks. Just remember that the dolomite will help adjust initially, but that it's true adjustment to PH takes time like everything else.

You can mix a little baking soda in with your water to help raise PH, it works well for me. Just be sure to use a tiny bit and raise it slowly.

Have you been PHing the water you use?