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Testing pH

Testing pH

Testing your pH will make sure that you’re always allowing the plant to uptake the nutrients you give them. You can give your plants the proper dose of nutrients each time, but if your pH is off she may not be up taking some of them and this can hurt your plants.

You might hear of growers getting lucky and never testing their pH. I find that there are two reasons for this. First, they are new and probably growing in soil. Second, their tap water is around 7.0 pH. I found that’s where my tap water usually hovers around.


You have few options for testing pH:

1. You can grab a pH kit for fairly cheap and they usually come with a liquid to test pH as well as two solutions that either raise or lower your pH. You’ll want both solutions called pH up and pH down regardless of your means of testing.

2. The liquid reader works by changing the water’s color and having you judge it against a color spectrum that looks like

pH valueColor indicator
4.0 Red
5.0 Orange
6.0 Yellow
6.5 Brown
7.0 Light Green
8.0 Dark Green


I personally recommend a pH meter that will give you a digital reading within a 0.1 resolution instead, but I started with the liquid and still sometimes use it. I recommend a tester because the pH range I give you may seem small, but they are not! A pH of 5.0 is ten times more acidic than a pH of 6.0. You’ll find both cheap and expensive meters and I’ll be up front, pH meters are super fickle, even the ones found in science labs. The cheap ones are still better than the liquid readers though and both are way better than none.


Important note:
for soil growers. If your water runoff is coming out under a pH of 6.0, you can use lime which will help buff your soil back to a neutral pH of 7.0.
Important note for soilless growers. There some debate about how important pH runoff is. I’ve seen people say “save your sanity and don’t worry” and I definitely know what they are talking about. I’ve had some grows in coco coir where despite how much water pH’d at 6.2 I gave, my runoff would always read under 5. This rarely happens to me and I never saw nutrient issues stemming from such a low pH for runoff. My advice is to carefully watch your plants, if you don’t see issue then don’t worry about it too much.