Why a Sustee Can’t Be Compared to a Metal Water Meter Probe.

If you’ve ever struggled with overwatering, underwatering, yellow leaves, fungus gnats, or root rot — you’re not alone. Most plant problems begin with incorrect watering.

That’s also why traditional metal moisture meters often create confusion.

At first glance, a Sustee and a metal probe water meter may appear similar. They both go into the soil and help guide watering decisions. But the way they work is completely different — and understanding that difference can dramatically improve plant health.

The Biggest Difference: What They Actually Measure

Traditional metal moisture meters measure electrical conductivity (EC) between two metal probes.

In simple terms:

• Wet soil conducts electricity
• Dry soil conducts less electricity
• The meter estimates moisture based on resistance

The issue is that conductivity changes depending on:

• Soil type
• Fertiliser levels
• Mineral salts
• Soil density
• Potting mix ingredients

That’s why metal probes often produce inconsistent or misleading readings.

A Sustee works differently.

Instead of measuring conductivity, Sustee measures plant-available water (pF value)— the moisture that roots can actually access and use. 

That distinction matters enormously.

How Sustee Actually Works

Sustee was developed in Japan using agricultural moisture science based on something called pF value.

Now, “pF value” sounds technical — but the concept is simple:

pF value measures how hard a plant has to work to pull water from the soil.

• Low pF = soil is very wet
• High pF = soil is becoming too dry

Plants grow best within a specific moisture range where roots can absorb water easily while still getting oxygen.

Too wet? Roots can suffocate and rot.
Too dry? The plant becomes stressed and dehydrated.

Sustee is calibrated to monitor this ideal moisture zone and indicate when the plant is approaching the point where watering is needed.

That’s why it works across almost all plant types and potting mixes.

Why Sustee Works Across Different Plants

One of the biggest misconceptions in plant care is that every plant needs completely unique watering timing.

In reality, environmental conditions play a massive role:

• Temperature
• Humidity
• Airflow
• Pot size
• Light levels
• Season

Sustee responds to the actual moisture available in the root zone under those changing conditions.

That means:

• Plants dry faster in summer
• Slower in winter
• Faster in terracotta pots
• Slower in dense potting mix

Sustee adapts naturally because it’s reading root-zone moisture continuously.

Sustee Mimics Root Behaviour

Inside every Sustee is a special refillable absorbent core that draws moisture from the soil through capillary action — similar to how roots absorb water. 

After watering:

• The indicator turns blue
• As available moisture decreases, it gradually returns to white

Blue = enough available water

White = time to water

No batteries.
No electronics.
No interpretation.

Just a simple visual indication based on real root-zone conditions.

Why Metal Probe Meters Often Cause Problems

Metal moisture probes are usually inserted briefly for a reading, then removed.

This creates several problems:

• Readings vary depending on insertion depth
• Different parts of the pot can give different results
• Salts and fertilisers interfere with readings
• Probes corrode over time
• Dense or chunky potting mixes reduce accuracy

Many gardeners end up watering “just in case” — which is exactly how root rot begins.

Sustee stays in the pot permanently, monitoring moisture consistently where it matters most: around the roots.

Sustee vs Metal Moisture Meter: The Bottom Line

A metal probe tells you whether soil is electrically conductive (EC).

A Sustee tells you whether your plant can still access usable water (pF).

That’s a very different thing.

If you want healthier roots, fewer watering mistakes, and stronger plants long-term, understanding this difference is critical.

Because most people don’t kill plants from neglect. They kill them with watering mistakes. And that’s exactly what Sustee was designed to prevent. 🌱

Give Your Plants a Chance. Shop the Sustee HERE