How to Water Living Soil: Moisture, Drybacks & Sensors
Updated: Oct 28
In this guide: Moisture and dryback · Watering decisions · Sensors
At Whole Plant Collective, we believe learning how to water living soil is as important as choosing the soil itself. Water supports roots, helps move dissolved nutrients and supports the organisms that help cycle nutrients.
If you’re looking for a ready-to-use peat-free mix, explore our Living Soil Potting Mix.
The aim is to keep the growing medium moist enough for plants and soil life while avoiding prolonged saturation that can reduce air around roots. There is no single watering schedule or moisture reading that suits every mix, container, plant and growing environment. Observation is more useful than a rigid target.
Moisture and air in living soil
Living soil is a growing medium with biological activity. Water helps dissolve and move nutrients, but the pore spaces between soil particles also need air. When soil stays saturated, water can fill many of those spaces and limit oxygen around roots. At the other extreme, allowing a container to become excessively dry can stress plants and slow some biological activity.
What is a dryback?
A dryback is the reduction in soil moisture between watering events. Plants use water and some moisture evaporates, so the growing medium gradually dries after watering and drainage.
A gradual dryback can help restore air-filled pore space. Excessive drying can stress plants, though, and the rate of drying changes with soil structure, container size, plant size, temperature, airflow and growth stage. Rather than aiming for a fixed percentage or interval, learn how your own soil behaves.
How to water living soil: read the plant, soil and pot
In larger containers, the surface alone can be misleading. The top may look dry while the root zone is still moist, or the surface may appear damp while another area is drying. Combine several simple checks before deciding whether to water.
Check moisture a little below the surface as well as at the top.
Lift the container, when practical, and notice how its weight changes after watering and as it dries.
Watch the plant over time and look for patterns rather than treating one symptom as a diagnosis.
If you use a sensor, keep it in a consistent position and record readings alongside watering events.
When you water by hand, apply water gradually and notice whether it soaks in evenly. If the soil has become very dry, a slower application may help you see how the growing medium responds. Avoid using a preset volume without considering container size, drainage and current conditions.
Using soil moisture sensors in living soil
Moisture sensors can help you see changes in the part of the root zone around the probe. They do not measure every part of a pot, and their readings should be considered alongside plant response, container weight and the soil itself.
Ecowitt WH51 and WH51L
The Ecowitt WH51 and WH51L are wireless soil-moisture sensors. The probe measures the soil around its position; the WH51L uses a separate cable so the probe can be placed lower in a container. Ecowitt provides custom calibration options for adapting readings to different soil types.
In my own living-soil setup, readings around 29–39% have been a useful working range. That is my experience with my conditions, not a universal target. Soil type, probe placement and calibration affect how useful a percentage reading is. I keep the probe in a consistent position, away from the container wall and direct watering points, and compare its trend with the plant and pot.
Blumat Digital tensiometer
The Blumat Digital takes a different approach: it measures soil-water tension in mbar rather than reporting a moisture percentage. As soil dries, water is generally held more tightly and the tension reading rises. This can offer another view of water availability, but the reading depends on the growing medium and should not be treated as a direct conversion to a sensor percentage.
I have limited experience with the Blumat Digital, so I would follow the manufacturer’s preparation and placement instructions. The manufacturer advises soaking the ceramic tip before use and allowing time for a reading to settle. If the display shows implausible readings, its FAQ describes resetting calibration; the instrument also needs periodic refilling during use.
You do not need either device to grow successfully in living soil. They are tools for understanding changes beneath the surface, not replacements for observing your plants and soil.
Hand watering or automated irrigation?
Hand watering
Hand watering is a useful way to learn how a growing medium absorbs water. It gives you a chance to check container weight, observe the soil surface and notice whether water is spreading evenly. The trade-off is consistency: it can be harder to keep several containers on the same routine, and it is easy to pour too quickly.
Drip and automated irrigation
Drip systems can save time and deliver water gradually, especially across multiple containers. But automation does not guarantee suitable watering. A fixed schedule may deliver too much or too little as plant demand and conditions change. Emitter position and flow rate also affect how evenly water moves through a large container.
If you use automated irrigation, check that it is delivering water consistently and monitor how the root zone responds. Whether you choose hand watering or automation, the goal is to avoid prolonged saturation and excessive drying.
Build a consistent watering routine
Start by observing what happens after watering and drainage. Record watering events and sensor readings if you use them, and note how the plant, pot and soil change. Over time, you will begin to recognise how temperature, airflow, plant size and container volume affect drying.
Change one variable at a time where possible.
Compare readings from the same probe position.
Use sensor trends as one clue, not as an automatic watering command.
Adjust for your soil mix, container, plant and environment.
The most useful routine is one that responds to the actual growing medium in front of you, rather than someone else’s schedule.
A grower’s note for flowering and fruiting plants
During the flowering phase of growth, when plants are producing fruits & flowers it’s important not to flood the soil with large volumes of water in one go. This can shift the microbiology in your soil to an anaerobic state negatively impacting fruit & flower set.
Frequently asked questions
How often should I water living soil?
There is no single interval that works for every living-soil setup. Check moisture below the surface, consider container weight, and watch how your plants respond. Water when the growing medium and plant need it, not only because a calendar says so.
What does dryback mean in soil?
Dryback is the gradual reduction in moisture after watering as plants use water and some evaporates. A suitable dryback depends on the growing medium, container, plant and environment; excessive drying can cause stress.
Are soil moisture sensors accurate in living soil?
A sensor reports conditions around its probe, and the reading can depend on soil type, placement and calibration. Keep it in a consistent position and use its trend alongside other observations rather than relying on one number.
Explore living soil and soil care
Starting with a living soil potting mix? Explore our Living Soil Potting Mix. If you are maintaining soil between cycles, read our living-soil re-amend guide and explore the Replenish Mix.
If recurring growing issues remain, our Basic Soil Biology Test and Soil Chemistry Test can help assess other aspects of soil. These tests do not measure moisture.
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