Soil sample jar

A sample beaker with fixed markings for testing your potting mix. Water to C, soil to A, shake and let it settle.

Why you cannot measure soil directly

A pH or EC meter measures a liquid. Soil is not one, and that is the problem: the values are in your potting mix, but they are bound up in moisture you cannot simply extract.

The answer is to make a sample in which the soil releases its values into water, at a fixed ratio, so the result means something and can be repeated. That is exactly what the markings on this beaker are for.

The method:

1. Fill the beaker with distilled water to line C. Do not use tap water: it already carries salts and its own pH, and you would be measuring those too.
2. Add soil to line A. Take the sample at root level, not from the top layer.
3. Shake for one to two minutes. This is the step where the soil releases its dissolved salts into the water.
4. Let it stand for five minutes. The soil sinks and a clear layer of liquid is left on top.
5. Measure in that top layer with your pH or EC meter.

Because the ratio of water to soil is the same every time, you can compare readings with each other. That matters more than the absolute value: you want to see whether pH in your pot is drifting or salts are accumulating, and you only see that by repeating the same measurement.

Technical Specifications:

• Type: beaker with fixed markings A and C
• Use: preparing a potting-mix sample for pH and EC measurement
• You also need: distilled water and a pH or EC meter

Frequently asked questions

Why distilled water?
Because tap water has its own pH and conductivity. Those would be added to what you are trying to read from your soil.

Can I do this with coco or rockwool?
Yes, the principle is the same. Bear in mind each medium releases differently, so only compare readings within the same medium.

Can I measure in the pot directly instead?
With a meter built for it, such as a soil pH pen or a multimedia meter. This beaker is the answer if you have an ordinary liquid meter.

How often should I do it?
Every week or two gives a good picture of the direction your pot is moving in.