Soil PH / Lime Question

Hello everyone,

I'm 3 weeks into my 2nd grow and need a bit of advice...

I'm using 90% ProMix BX ans 10% red worm castings purchased from a local farmer. I'm using distilled water that comes with a PH off the shelf around 6.5.

At about day 15 my plants started to yellow from the bottom leaves up and the leaves started drooping and "hugging" the plants fairly tightly. Eventually growth slowed to a crawl and the 1 & 3 leave internodes completely died. Every thread I read that looked somewhat similar said over or under watering. I'm 95% sure that this isn't my problem. I use the "how heavy is my pot" method and water roughly every 3-5 days.

I think that my problem is that the PH of my runoff water is measuring 4.0 causing a N deficiency (thank you Internet). I made a trial batch of soil and watered samples with higher and higher PH distilled water (using PH+) until it was off the chart of my PH kit (9.0ish??) and the runoff water was still very low...closer to 5.0.

I did my best to check the PH of just the worm castings and it was in the 4.0 range. The ProMix is closer to 6.0. It seems like the low PH of the mix is driving the water PH down no matter what I do.

What is the best way to get the PH of the soil up? The guys at the hydro shop didn't have good answers for me.

I added 2 heaping tablespoons of powdered dolomite lime per gallon of soil when I transplanted 2 days ago. The runoff still read low when I watered them, but they look like they're rebounding (sorry for no pictures).

I was very afraid of burning my plants with the lime. If the 2 tablespoons doesn't get me in the 6.5 range, how much can I add before it's a problem?

Any advice is much appreciated!

Thanks,

Sheepdog

The lime may take some watering to change the ph of the soil. U said u made a trial batch of soil, did u add the lime to it? Keep checkin that runoff and lemme know what happens though.

are you flushing?

You need to be running a lot of water thru the pots to change the pH.

So u think it may be the worm castings messing with the pH? Cuz usually when it gets off, then you can just run correctly pHed water thru at 3x the pot volume and the problem is usually solved if you don't do it too late. If you can't stableize the pH with just water I have heard that the dolomite lime pellets are good. Just make sure to use a ton of water and check the runoff and you will know for sure with is up.

I was wondering that myself edux, maybe flushing with tap water?

Yeah, I think the castings are a contributor, but the soil is a bit low too. The castings at the hydro shop are balanced already.

My trial batch initially did not have lime & I was not able to get the PH up just by soaking the soil, not flushing it.

I think rickjames may be on to something. I think it took some time soaking for the lime to do it's job. They really have taken back off since I added the lime 3 days ago.

I'll be watering tonight so I'll try to get a good runoff water reading (the kit w/ drops sorta sucks for that).

So, Are you saying that if I do a 3x flush with tap water, that it'll roughly equalize the PH to the tap water? I'd like to figure out the lime ratio so I don't have to flush every time I transfer.

It's crazy how a PH problem affects plants differently! I'll try to get some pics up. Thanks for the advice!

It should take on the ph of the water when u flush properly, 3x water-to-soil. Ph can really fuck ya if u don't got it right! Too high and u'll lockout this, too low and u'll lockout that.... Adding the lime should relieve u of the ph stress though. I use one gallon pots for my soil, mixed with 2tbs of lime and my ph is real close to 7!