What is pH — and how (and why) should you control it when growing marijuana?

in #growing17 hours ago

Why do you even need to mess with pH?

Simple — at certain pH levels, your plant can absorb certain nutrients. Technically, pH means “potential of hydrogen,” but to keep it simple, it’s basically a measure of how acidic or alkaline your water or solution is

  • If your pH is below 7, the medium is acidic — the lower it is, the more acidic

  • If your pH is above 7, the medium is alkaline — the higher it is, the more alkaline

  • Neutral pH is 7

How to adjust pH?

Yeah, you can lower pH with lemon juice, but it only works for a few hours — then pH starts creeping back up. It’s not a good long-term fix, especially if you want a stable buffered solution. Same thing with raising it — baking soda can raise pH, but that’s also a short-term band-aid

Basically, these are just temporary hacks — like if your proper pH up/down hasn’t arrived yet.

For stable results, always use proper pH-adjusting solutions. I personally use GHE (Terra Aquatica), but there are tons of cheaper analogs out there

From my experience, pH Up is rarely needed. It depends on your water, of course, but during veg you almost never need it. So don’t waste cash — grab pH Down first, and get the other one later if you really need it

How to measure pH?

You can use test strips — cheapest option, but not very accurate.

I use a digital pH meter. There are a few types:

👉 Cheaper ones — they work fine. I’m not gonna explain how to calibrate it — there are tons of YouTube videos for that, and calibration depends on the model. You’ll need distilled water for calibration. Calibrate it every 3 months. Honestly, at that price, it’s often easier to just buy a new one ;)

👉 More expensive models — they’re more accurate and need calibration way less often


These usually also measure PPM and water temperature

How to store a pH meter?

If you’re using it daily — just close the cap after use so the electrode stays moist.

That’s what I do: cap it, toss it on the shelf, done

But if you wanna be a perfectionist — the proper way is to store it in a potassium chloride (KCl) solution made with distilled water.
Mix 23 grams of KCl per 100 ml of distilled water. Pour it into a small cup and dip the pH meter in
You can even soak a bit of sponge with that solution and stick it inside the cap