Plant moisture meter: Should you use one for watering?

Many plant lovers know the problem: some houseplants are accidentally drowned, while others suffer from drought. To avoid watering mistakes, some people use moisture meters for plants. But how do these devices work, and are they really helpful when watering?

How moisture meters work

Plant moisture meters are designed to indicate how moist the soil is in order to prevent over- or under-watering. However, they do not measure the moisture content directly. Instead, they measure the electrical conductivity of the substrate:

• High conductivity: Moist soil conducts electricity well, which the device displays as "wet".

• Low conductivity: Dry soil conducts less well, which is displayed as "dry".

Since the actual water content is not measured, various factors can influence the measurement.

susceptibility to errors and limitations

Moisture meters are susceptible to measurement errors because they only measure the conductivity of the soil. Factors such as fertilizers, salinity or different types of substrate can change the conductivity and thus distort the measured values. In addition, they do not provide any information about the moisture in deeper layers of soil, which can be particularly problematic with larger pots.

Alternative methods for moisture determination

Instead of relying solely on technical devices, simple methods can help determine the moisture content of the soil:

• Finger test: Stick a finger about two centimeters deep into the soil. If it feels dry, it is time to water.

• Wooden stick: Stick a wooden stick deep into the soil and pull it out. If soil sticks to it or the stick is moist, the plant does not need water yet.

• Pot weight: Lift the pot. A light pot indicates dry soil, a heavy pot indicates moist soil.