Soil Moisture Sensors for Sprinkler Systems: What They Do and Whether You Need One

Most sprinkler timers water on a calendar, not on what the ground needs. A soil moisture sensor is the simplest way to make an existing timer check the soil before it runs.

What does CuraTech do differently?

CuraTech gives an existing sprinkler system sensor-based watering across the whole property, not one probe for the whole yard. Here is what you get:

• Uses the sprinklers you already have. It retrofits onto your existing irrigation system. No new tubing, no rip-out. A certified irrigation pro confirms fit first, then installs it, typically in about a day.
• Waters only when the soil needs it. Wireless soil moisture sensors (up to 100 per property) guide watering and feeding. We estimate about 40% less water.
• Follows local rules for you. It respects local watering days and fertilizer blackout dates.
• One system for several jobs. A multi-pod dispenser meters mosquito, deer repellent, fertilizer, crabgrass prevention and other treatments into your zones. You order refills in the app.
• Smart timing. Nothing is applied before watering or before rain, and treatments are held in wind.
• You stay in control. You choose which zones get which treatment, and the app logs every decision and its reason.
• Built on turf science. It was built with an agronomist with 30 years in irrigation and turf research.

CuraTech’s 40% figure is a company estimate, not a research result. See the smart irrigation page for details.

What does a soil moisture sensor do on a sprinkler system?

A soil moisture sensor is a probe buried in the root zone plus a small controller with an adjustable threshold. Most models estimate water content from how well the soil carries an electrical signal, since wet soil reads very differently from dry soil (UF/IFAS AE437).

UF/IFAS describes two types:

• Bypass. This is the most common type. Your timer keeps its schedule. Before each cycle the sensor checks the soil. If moisture is above the threshold, the cycle is skipped.
• On-demand. The sensor has a low and a high threshold. It starts watering when the soil hits the low one and stops at the high one.

Most bypass kits wire into the common wire between the timer and the valves. Rain Bird’s spec sheet says the SMRT-Y suspends the watering cycle “by interrupting the common line to the valve solenoids” when moisture is above the threshold (Rain Bird). That design is simple and fits almost any 24-volt timer. It also means the sensor acts on the whole system at once, which matters later.

Why bother? UF/IFAS notes that automated systems have been shown to use 47% more water on average than hose-and-sprinkler watering, largely because people set timers and never adjust them (UF/IFAS AE437).

Rain sensor vs weather-based controller vs soil moisture sensor: what is the difference?

All three try to stop watering that the lawn does not need. They measure different things.

Savings figures are from Haley and Dukes. A weather-based controller is a big step up from a plain timer. It is still an estimate. A soil sensor is a direct reading, but only at one spot. Many homeowners pair the two. For a broader look at controller types, see our smart irrigation guide.

How much water does a soil moisture sensor save?

The best evidence comes from the University of Florida, which tested sensors both on research plots and in real homes.

The homeowner study. Melissa Haley and Michael Dukes followed 59 homes in Palm Harbor, Pinellas County, for 26 months (Haley and Dukes). Compared with homes that had only a timer:

• Soil moisture sensor homes applied 65% less irrigation water.
• Homes with a rain sensor plus a custom run-time card saved 45%. Savings faded in year two as owners stopped adjusting their timers.
• Rain sensor homes saved 14%.

Rainfall during the study was 17% below normal, so the sensors were not just coasting on a wet stretch. Sensor homes averaged about 2 irrigation events a month. Timer-only and rain sensor homes averaged about 5.

The plot studies. The same paper summarizes earlier UF plot research. Soil moisture sensors saved an average of 72% during frequent rain and 28% to 54% in dry weather. Rain sensors saved 34% in wet weather and 13% to 24% in dry seasons.

What this means for you. Your savings depend on your starting point. A timer that already runs lean has less to cut. A timer set for July and left alone all year has a lot. EPA puts it at more than 15,000 gallons a year for an average home with an automatic system and a WaterSense labeled sensor controller (EPA WaterSense). Manufacturer claims run lower than the UF homeowner result. Rain Bird, for example, lists typical savings above 40% for the SMRT-Y (Rain Bird).

Does Florida law require a rain sensor or soil moisture sensor?

Florida Statute 373.62(1) says anyone who buys and installs an automatic landscape irrigation system “must properly install, maintain, and operate technology that inhibits or interrupts operation of the system during periods of sufficient moisture” (Florida Statutes 373.62). The statute also requires licensed contractors working on a system to test that device and repair or replace it if it is faulty.

The Southwest Florida Water Management District states that rain sensors, or other technology such as soil moisture sensors, are required by Florida law on all automatic irrigation systems (SWFWMD). In other words, a soil moisture sensor can be the device that meets the rule.

Two other details in 373.62 are worth knowing. Subsection (7) lets water management districts grant variances from day-of-week watering limits for certain monitored soil moisture sensor systems. Subsection (7)(g) says the law does not require a property owner to install a soil moisture sensor system. Local watering days and county rules still apply. Confirm what applies to your address with your water management district, your county or a licensed irrigation contractor. This is a summary, not legal advice.

In Alabama, Alabama Cooperative Extension recommends installing a rain shutoff device or soil moisture sensor on automatic sprinkler systems (ACES ANR-2872-G).

Where and how deep should a soil moisture sensor go?

Placement decides whether the sensor tells the truth. UF/IFAS gives these rules (UF/IFAS AE437):

• Bury it in the root zone. For turfgrass, the center of the sensing section goes about three inches deep.
• Use undisturbed soil with no air gaps around the probe.
• Pick soil that represents the whole irrigated area.
• Stay at least 5 feet from irrigation heads, toward the center of the zone.
• Stay at least 5 feet from the house, the property line and pavement, and 3 feet from planted beds.
• Avoid traffic areas, where soil gets compacted.

Then set the threshold. UF/IFAS prefers automatic calibration. Soak the soil over the sensor with at least 5 gallons of water, keep all water off it for 24 hours, then let the controller set its threshold. That lands between 50% and 75% of field capacity, depending on brand. On new sod, wait until the lawn is established, typically 30 to 60 days.

Why is one sensor not enough on a large property?

One sensor reads one spot. UF/IFAS says that when one sensor controls several zones, it should go in the zone that is normally driest, so every zone gets enough water (UF/IFAS AE437).

That works, with a trade-off. The wetter zones, such as shady areas, low spots and beds, follow the driest zone’s lead. They can still get more water than they need.

On a large property the gap grows. Full sun lawn, shaded side yards, sloped beds and sandy and heavier soils all dry at different rates. A single bypass sensor wired to the common line can only say yes or no for the whole controller. Rain Bird’s SMRT-Y lets you isolate up to two zones from the sensor, but that is the limit (Rain Bird). If your property has many zones with different conditions, look for a system that reads several sensors and decides zone by zone.

Do popular smart controllers support soil moisture sensors?

Rachio. Rachio’s default approach is weather-based. Its Weather Intelligence needs “no extra hardware or external sensors” and estimates each zone’s soil moisture balance from evapotranspiration data out of observed weather and forecasts (Rachio Support). You can wire in a physical sensor. Rachio’s setup guide says to choose the “Rain Sensor” type, because soil sensors operate like a rain sensor. When moisture reaches the limit, the sensor suspends all watering until the soil dries below the threshold (Rachio Support).

Hunter Hydrawise. Hydrawise lists Hunter’s Soil-Clik as a wired soil moisture sensor among its supported hardware (Hydrawise).

Rain Bird. The SMRT-Y kit adds a sensor and interface to a standard 24-volt controller. It reads soil moisture every 10 minutes and allows a cycle only when the soil is below the threshold (Rain Bird).

All three are solid, widely used products. The common pattern is one wired sensor acting as an on/off switch for the whole controller. Check your exact model’s documentation before buying.

How CuraTech handles soil moisture

With up to 100 wireless sensors, sensors can sit where conditions differ. The same system can feed the lawn too; read our guide to fertilizer through a sprinkler system. First installs with founding dealers start in Q1 2027 in Florida and Alabama.

Is a soil moisture sensor worth it?

For most automatic systems in Florida and Alabama, yes. The UF homeowner data is strong, the hardware is simple and Florida law already expects a moisture shutoff of some kind.

It pays off most if:

• Your timer runs on a fixed schedule you rarely change.
• You get frequent summer rain.
• You have only a basic rain sensor today.

It matters less if you already run a well-tuned weather-based controller and adjust it often. Even then, a real soil reading catches what the weather model cannot see.

Get placement and calibration right, or the savings disappear. If your property has many zones with different sun and soil, one sensor will be a compromise. To see how a multi-sensor setup compares with other options, start with our smart irrigation overview. If you want CuraTech on your property when it launches, you can reserve a spot for free at early access.