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The tools

Eight tools. Every input, and every limit.

All eight run on the same eight sensor channels — nothing here is a separate purchase or a separate probe. For each one: the question it answers, what it reads, how much history it needs before it will say anything, and where it breaks down. That last part is not a disclaimer section. It is the reason you should believe the rest.

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All eight at both tiersNo tool is an add-on $4.99 / device / monthCancel any month

Part one · figures 01–03

What do I do tonight, and how long have I got?

The three tools you will actually open. One says what is wrong, one says whether to water and for how many minutes, and one says how many hours you have before it matters.

  1. 01 Lawn Health Score
  2. 02 Smart Watering Advisor
  3. 03 Dry-down Forecast
FIG.01

Diagnose

Lawn Health Score

“Something looks off. What should I actually fix first?”

A single number describing a lawn is a blunt instrument, and we are not going to pretend otherwise. The score exists to be glanceable; the useful output is the limiting factor printed beside it — the one weighted input dragging the number down hardest.

Five sub-scores are computed over roughly the last seven days and combined with fixed weights. The limiting factor is whichever sub-score has the largest weight multiplied by its shortfall from 100, so a mediocre score on a heavily weighted input beats a terrible score on a light one.

One device · last 7 days · weighted contribution Limiting factor
How the Lawn Health Score is assembled from five weighted sub-scores. A score of 78 out of 100. Moisture in band scores 61 and carries 35 per cent of the weight, so its shortfall pulls the total down by 13.6 points — more than the other four combined. Stability scores 88 at 15 per cent, heat and cold stress 91 at 20 per cent, light 74 at 15 per cent, and freshness and signal 96 at 15 per cent. Moisture is therefore named as the limiting factor. 78 OUT OF 100 LIMITING FACTOR ROOT-ZONE MOISTURE Moisture in band WEIGHT 35% · PULLS −13.6 61 Moisture stability WEIGHT 15% · PULLS −1.8 88 Heat & cold stress WEIGHT 20% · PULLS −1.8 91 Light WEIGHT 15% · PULLS −3.9 74 Freshness & signal WEIGHT 15% · PULLS −0.6 96 Bar length is the sub-score. The label underneath is what it costs the total.
Moisture scores 61 and carries the heaviest weight, so it pulls 13.6 points off the total — more than the other four shortfalls combined. That is what makes it the limiting factor, and it is why the advice is “fix the watering” rather than “your lawn is a 78”.
What it reads
  • Moisture in band — the fraction of samples inside your soil type’s range, with a soft penalty either side of it (35%)
  • Moisture stability — standard deviation of soil moisture; a spread of 25 %VWC takes this term to zero (15%)
  • Heat and cold stress — samples below 0 °C or above 32 °C are penalised in proportion (20%)
  • Light — mean lux against roughly 25,000 as a full-sun reference (15%)
  • Freshness and signal — full marks under two hours old, decaying to zero by 24 h; signal is 30% of this term (15%)
What it gives you
  • a score from 0 to 100
  • all five sub-scores, so you can see which one moved
  • the limiting factor by name
  • the number of samples the score was computed from
Before it can say anything
  • One reading. It will compute from the first uplink.
  • About seven days before it means much: stability needs a spread to measure, and light needs whole days.
  • Your soil type on the device record, or it assumes loam.
Where it falls down
  • It is a composite. Two lawns with identical scores can have nothing else in common — always read the limiting factor, never just the number.
  • The light term is a lux average standing in for a daily light integral. It is a proxy, and a probe under a shrub will report shade that the rest of the lawn does not have.
  • Freshness dominates when a sensor goes quiet. A score falling because nothing has arrived is telling you about your radio, not your grass — which is deliberate, so a dead sensor can never quietly report a healthy lawn.
  • It does not know about disease, grubs, dog urine, or the fact that you scalped it on Sunday.
FIG.02

Decide · the one the product is built around

Smart Watering Advisor

“Do I water tonight, and for how many minutes?”

This is the tool the product is built around. It computes today’s reference evapotranspiration with the FAO-56 Hargreaves equation, scales it by a grass crop coefficient to get your lawn’s actual demand, subtracts the rain your own gauge recorded in the last 24 hours, and converts what is left into minutes at your sprinkler’s output rate.

It is deliberately conservative. If your soil is already at or above the bottom of its band, or the rain has already covered the demand, it tells you not to water and shows you the arithmetic that says so.

Tonight’s water budget · worked end to end
The watering advisor's arithmetic, step by step. Reference evapotranspiration works out at 5.8 millimetres a day. Multiplied by a cool-season crop coefficient of 0.80 that is 4.6 millimetres of actual demand. No rain fell in the last 24 hours, so nothing is subtracted. The soil is fully depleted against its loam band, which adds a 6 millimetre top-up, giving 10.6 millimetres to apply — 0.42 inches. At a precipitation rate of 0.8 inches an hour that is a 31 minute run, starting at 5:30 in the morning. ET₀ reference Hargreaves, from Ra 16.8 · Tmax 29.4°C · Tmin 16.1°C 5.79 mm × Kc 0.80 = ETc cool-season grass coefficient — your lawn’s real demand 4.63 mm − effective rain nothing fell in 24 h; rain is discounted to 80% when it does 0.00 mm + depletion top-up soil at 19.4% against a 22–38% loam band — fully depleted 6.00 mm = APPLY 10.63 mm · 0.42 in ÷ 0.8 in/hr precipitation rate 31 minutes starting 05:30, before the sun is on it
Change any input and the answer moves: a spray head at 1.5 in/hr turns this same 0.42 inches into a 17-minute run. That is why precipitation rate is a device setting and not something we guess — a catch-can test beats every assumption on this page.
What it reads
  • Extraterrestrial radiation — computed from your latitude and the day of year, not assumed. With no location on file it falls back to a mid-latitude 16.8 mm/day.
  • Tmax, Tmin and Tmean from your own air-temperature channel
  • Crop coefficient — 0.80 cool-season, 0.65 warm-season
  • Effective rain — the last 24 hours only, discounted to 80%
  • Current depletion — where soil moisture sits against your soil type’s band
  • Your precipitation rate in inches per hour, to turn a depth into minutes
What it gives you
  • water or hold, and the reason either way
  • a run time in minutes
  • a pre-dawn start time — 05:30 local, to limit evaporation and leaf-wetness disease
  • ET₀, ETc, effective rain and depletion, all shown as numbers you can argue with
Before it can say anything
  • A day of air temperature with a real day–night swing. Without Tmax > Tmin it falls back to a flat 4.0 mm/day rather than guessing.
  • Soil type, grass type and precipitation rate set on the device. The default rate is 0.5 in/hr, which is a rotor; spray heads are much faster.
Where it falls down
  • Hargreaves is a temperature-only ET₀ model. It cannot see wind or measured solar radiation, so on a hot dry windy day it under-reads, and in a humid calm one it over-reads. It is the right trade for a sensor that has a thermometer and no anemometer, and it is the FAO’s own recommendation when only temperature is available.
  • It does not control your sprinklers, and that is deliberate. You or your existing controller do the watering, which keeps it compatible with a hose and a mechanical timer.
  • A single run is capped at 90 minutes. On badly depleted soil the honest answer is more than one cycle, and a 3-hour recommendation would mostly run off.
  • The crop coefficient is a grass coefficient. On vegetables, borders or shrubs the readings stay useful but treat the runtime as a starting point.
  • It has no rain forecast of its own. It reacts to rain that has fallen, not rain that is coming.
FIG.03

Decide

Dry-down Forecast

“How long have I actually got before this matters?”

Knowing you need to water tonight is useful. Knowing you have until Thursday afternoon is what lets you plan around a trip, a forecast, or the fact that you would rather not drag the hose out in the dark.

It finds the most recent peak in your soil-moisture series, takes everything after it, and fits a straight line through that falling segment. Extending the line to your soil type’s refill point gives the hours remaining. The fit quality is reported alongside, so you can see how much to trust it.

Root-zone moisture · loam · refill point 22% Measured Fit, extended Refill point
A dry-down forecast projected to the refill point. Soil moisture peaks at 31.6 per cent on day one, then falls. A straight line fitted through the falling segment drops about 2 per cent a day and reaches the 22 per cent loam refill point midway through day five — roughly 4.9 days from the peak. The measured curve is slightly above the fitted line late on, because real dry-down slows as soil dries while a straight line does not. 18% 22% 26% 30% 34% DAY 0 DAY 1 DAY 2 DAY 3 DAY 4 DAY 5 DAY 6 LAST PEAK — SEGMENT STARTS HERE NOW FORECAST 33 h to the refill point RATE −2.02 %/day FIT QUALITY r² 0.97
Look at the gap opening between the measured curve and the dashed fit after day three. That is the straight-line assumption showing its age: real soil gives up water fastest when it is wet. The forecast is therefore slightly early, which is the direction we would rather be wrong in.
What it reads
  • The falling segment only — from the most recent moisture peak to now
  • A least-squares fit through that segment, giving a slope in %VWC per day
  • The refill point for your soil type — 12% sand, 22% loam, 28% clay
What it gives you
  • hours until the refill point
  • the dry-down rate in %VWC per day
  • the r² of the fit, so a poor fit is visible rather than hidden
  • a plain-English diagnostic instead of a number when it cannot answer
Before it can say anything
  • At least four soil-moisture samples overall, and at least three since the last peak.
  • A trend that is actually falling. If moisture is flat or rising it says “no dry-down trend yet” rather than inventing one.
Where it falls down
  • It fits a straight line to a curve. Real dry-down is fastest when the soil is wet and slows as it dries, so a forecast made right after a soaking tends to be pessimistic.
  • It assumes the weather continues. A heatwave arriving tomorrow will beat the forecast; a cool cloudy week will leave you with more time than it said.
  • Watering, rain, or anything else that creates a new peak resets the segment — which is correct, but it means the estimate can move a long way in one uplink.
  • Immediately after a cycle there is no falling segment at all, so it will decline to answer for a few hours.

Figures 01–03, read04–08 to go

An interval

Five sentences this software will not say.

Every limit printed on this page has a mirror image, and the mirror image is the reason the limit is worth reading. These five are what the numbers above actually buy you.

  1. It will not tell you the lawn is fine because the sensor stopped talking. The health score’s freshness term is full marks under two hours old and zero by 24 — so silence pulls the number down instead of coasting on the last good reading.

  2. It will not turn your sprinklers on. Nothing is wired to your valves. You get a start time and a run time; you, or the controller you already own, do the watering. A hose and a mechanical timer are a supported setup.

  3. It will not ask you to run a three-hour cycle. A single recommendation is clamped at 90 minutes. Badly depleted soil honestly needs more than one cycle, and a three-hour run would mostly leave the property.

  4. It will not invent a dry-down trend out of a rising curve. Under four moisture samples, or under three since the last peak, it returns “no dry-down trend yet” and no number at all.

  5. It will not call a thunderstorm a burst pipe. Rain is summed across the whole two-hour detection window before a leak is ever raised — which is also why hand-watering you did not log looks exactly like one.

Part two · figures 04–06

What actually happened out there?

Irrigation is almost never measured after the valve shuts. These three run without being asked: one looks for things that have broken, one checks the water reached the roots, and one does the arithmetic on what you saved.

  1. 04 Anomaly & leak detection
  2. 05 Infiltration Efficiency
  3. 06 Water Savings
FIG.04

Diagnose

Anomaly & leak detection

“Is something broken out there that I cannot see?”

Five separate detectors run over your reading history. They look for shapes rather than thresholds, which is what lets them find a stuck valve that no single reading would ever reveal.

The leak detector is the one that earns its keep. Soil moisture climbing sharply when no rain was recorded is the signature of a stuck valve or a burst line — and rainfall is summed across the whole detection window before anything is raised, so a passing storm is never mistaken for a burst pipe.

Five detectors · the shape each one is looking for
The signature each of the five anomaly detectors looks for. Five small panels. Leak: a flat moisture trace that steps sharply upward with no rain recorded. Flatline: a trace that is perfectly horizontal, with no noise at all. Dropout: a trace with a gap in the middle where no readings arrived. Battery: a slowly declining voltage line extended by a dashed projection to the 3.3 volt cutoff. Spike: a noisy trace with one single sample far outside the rest. LEAK moisture +6% in 2 h, rain < 0.2 mm CRITICAL rain 0.0 mm FLATLINE sd < 0.01 over 12 samples WARNING DROPOUT gap > 3× median interval WARNING nothing arrived BATTERY fit projected to 3.3 V CRITICAL 3.3 V SPIKE air temp at |z| ≥ 4 INFO z = 4.4 All five run over the same reading history. None of them needs you to configure anything. Rainfall is summed across the WHOLE window before a leak is raised — a storm is never a burst pipe.
What it reads, and what each one needs first · the scan itself runs at three readings
Detector The signature it looks for Before it can fire Severity
LEAK moisture +6% in 2 h, rain < 0.2 mm nothing beyond the three-reading floor critical
FLATLINE sd < 0.01 over 12 samples 12 consecutive moisture samples warning
DROPOUT gap > 3× median interval 3 intervals, to have a median at all warning
BATTERY fit projected to 3.3 V 6 battery points, and it only speaks under 21 days critical
SPIKE air temp at |z| ≥ 4 8 air-temp samples with sd > 0.5 info

Scroll the table sideways

What it gives you
  • a list of findings, each with the evidence that raised it
  • the magnitude and the timestamp, not just a label
  • a severity, so a dying battery and a burst pipe are not the same colour
Where it falls down
  • The leak rule wants 6 %VWC inside two hours. A slow weep that lifts moisture by two per cent over a day will not trip it — it looks exactly like a light watering.
  • Hand-watering you did not log looks like a leak, because from the soil’s point of view it is identical to one.
  • Flatline needs a genuinely dead probe. A probe drifting slowly out of calibration still varies, so it passes.
  • Spikes are reported as information, not proof. A z-score of four is unusual, not necessarily wrong.
  • It scans the history it has. A device that has never reported cannot have an anomaly detected on it — that is what the offline alert is for.
FIG.05

Verify

Infiltration Efficiency

“Did the water I paid for actually reach the roots?”

This is the measurement almost nobody takes. A controller reports a completed cycle whether the water soaked into the root zone, sheeted off down the driveway, or beaded on hydrophobic thatch and evaporated by ten in the morning.

For every logged cycle it takes the moisture immediately before and immediately after, divides the gain by the depth applied, and gives you a coefficient in %VWC per inch. One number is interesting; the trend across cycles is the diagnosis.

Six cycles · %VWC gained per inch applied Coefficient Trend
Infiltration coefficient declining across six watering cycles. Six cycles a week apart, each applying about four tenths of an inch. The moisture gained per inch falls steadily from 14.6 per cent on the fourth of June to 7.9 per cent on the third of July. The last cycle is below the 8 per cent line at which the tool reports possible runoff or compaction. The applied depth barely changed, so the water is going somewhere other than the root zone. RUNOFF LINE 8% 0 4 8 12 16 14.6 Jun 04 0.42 in 13.9 Jun 09 0.40 in 12.4 Jun 15 0.42 in 11.1 Jun 21 0.41 in 9.6 Jun 27 0.42 in 7.9 Jul 03 0.40 in %VWC PER INCH Applied depth is near-identical every cycle. Only the gain is falling — that is the signal.
Trend classified as declining once the fitted slope passes −0.05 per day across four or more cycles. On this zone the likely causes are thatch build-up or compaction, and the usual answers are aeration or splitting the cycle in two with a soak between.
What it reads
  • Moisture before and moisture after each cycle, captured from the readings surrounding it
  • The depth applied — either entered directly, or minutes multiplied by your precipitation rate
  • A regression across cycles to classify the trend as improving, stable or declining
What it gives you
  • a mean coefficient in %VWC gained per inch applied
  • a trend, once there is enough history to fit one
  • a diagnostic naming runoff or compaction when the coefficient is low
  • the sample count, so a coefficient from one cycle is visibly from one cycle
Before it can say anything
  • At least one logged cycle that has moisture readings either side of it.
  • At least four cycles before a trend is fitted; below that it reports “stable” rather than reading noise as a slope.
Where it falls down
  • The “low infiltration” diagnostic fires below 8 %VWC per inch, and that figure depends on your soil texture and how deep the probe sits. Read the trend, not the absolute. A sandy soil legitimately reads lower than a loam.
  • It measures at one point. Water running off the far corner of the zone is invisible to a probe in the middle of it.
  • It needs cycles to be logged. Water by hand without recording it and there is nothing to compute against — worse, the anomaly scanner may read it as a leak.
  • A cycle that runs while it is raining produces a meaningless coefficient, because the rain is in the numerator too.
FIG.06

Verify

Water Savings

“Is this thing actually saving me anything?”

Gallons and dollars, computed from cycles you actually ran against a baseline schedule. The conversion itself is geometry rather than an assumption: one inch of water over one square foot is 0.623 gallons.

This is the tool with the most room to flatter us, so it is the only one whose assumptions are printed before its figure rather than after it. Read them first, then decide how much of the number to quote to anyone.

Where it falls down
  • The baseline is a model, not your old bill: a set-and-forget controller applying 1.5 inches a week across the period. If your previous schedule was thriftier than that, this overstates the saving.
  • It is floored at zero and never goes negative. A week where you watered more than the baseline reports no saving rather than a loss, which is a real asymmetry in our favour — treat the number as a ceiling.
  • Log nothing and it reads as though you applied nothing, which looks like a total saving and is simply an empty log.
  • Rainfall is not credited to either side. That makes it conservative in one direction and crude in both.
  • It is arithmetic on numbers you supplied, not a measurement of your utility bill. The only figure here that is not an assumption is 0.623.
30 days · 2,500 sq ft · $6.50 per 1,000 gal
Modelled baseline water use against actual logged use over 30 days. A set-and-forget baseline of 1.5 inches a week over 4.3 weeks applies 6.45 inches, which across 2,500 square feet is 10,046 gallons. The cycles actually logged applied 3.28 inches, or 5,109 gallons. The difference is 4,937 gallons, worth $32.09 at $6.50 per thousand gallons. BASELINE MODEL 1.5 in/week × 4.3 weeks 10,046 gal YOU ACTUALLY APPLIED 7 logged cycles, 3.28 in total 5,109 gal DIFFERENCE 4,937 gal · $32.09 gallons = depth (in) × area (ft²) × 0.623 — the only line here that is geometry rather than assumption The baseline is a MODEL of a controller nobody adjusted. It is not your old water bill.
If your previous schedule was already thriftier than 1.5 inches a week, this figure overstates what you saved. It is also floored at zero, so a heavy week never shows as a loss. Both asymmetries run in our favour, which is exactly why they are printed here rather than in a footnote.
What it reads
  • Your logged cycles — both advisor-recommended and manually recorded
  • The depth each one applied
  • Your zone area in square feet; with none set it assumes 1,000
  • Your water rate per thousand gallons, off your own bill
  • The window you asked about — the baseline is scaled to that window, never inferred from how often you happened to water
What it gives you
  • gallons not applied over the period
  • dollars at the rate you entered
  • the baseline and your actual usage side by side, both in gallons
Before it can say anything
  • Logged watering events. Nothing else can be compared.
  • A queried window, which the dashboard always supplies.

Part three · figures 07–08

Everything that is not watering.

Mowing, feeding and seeding are driven by soil temperature rather than by the month — and once there is more than one sensor on the account, the interesting number is the gap between two zones rather than either zone on its own.

  1. 07 Mow, fertilize & seed readiness
  2. 08 Multi-device Compare
FIG.07

Time the rest

Mow, fertilize & seed readiness

“Is this weekend the right weekend to do the job?”

Grass does not read calendars. Germination and growth are driven by soil temperature, and soil temperature lags the air by hours and the season by weeks — which is why seed sown on the date the bag suggests so often fails.

Each of the three jobs gets a 0–100 readiness and, more usefully, a sentence explaining what is holding it back. The windows differ by grass type, because they genuinely differ by grass type.

Soil temperature windows · your soil reads 63°F Open now Shut
Soil-temperature windows for seeding and fertilizing, by grass type. A soil-temperature axis from 40 to 95 degrees Fahrenheit. Cool-season seeding and fertilizing both run from 50 to 64.4 degrees. Warm-season seeding runs from 69.8 to 84.2 and warm-season fertilizing from 64.4 to 84.2. A marker at 63 degrees sits inside both cool-season windows and below both warm-season ones, so a cool-season lawn is ready to seed and feed today while a warm-season lawn is not. 40°F 50°F 60°F 70°F 80°F 90°F Seed — cool-season KBG, fescue, rye 50–64°F Seed — warm-season Bermuda, zoysia 70–84°F Fertilize — cool-season active growth, no burn 50–64°F Fertilize — warm-season active growth, no burn 64–84°F YOUR SOIL · 63°F Mowing is judged on moisture and rain, not on this axis.

Same lawn, same day, two different answers depending on what is planted in it. A cool-season lawn is in its window for both jobs; a warm-season lawn is still six degrees short of germinating. That is why grass type is a device setting rather than something inferred.

What it reads
  • Mean soil temperature at root depth, against the window for your grass
  • Mean air temperature — above 32 °C mowing stresses the turf
  • Current soil moisture against your band — too wet ruts and clumps, too dry burns fertilizer and kills seedlings
  • Recent rain total — over 2 mm delays mowing, over 8 mm risks washing granular fertilizer off
What it gives you
  • a readiness score for mowing, for fertilizing and for seeding
  • the specific reason each one is being held back
  • the target soil temperature to wait for, when soil is the blocker
Before it can say anything
  • Soil temperature above all. Without it, fertilize and seed return a neutral 50 and say so explicitly rather than guessing.
  • A current moisture reading for the wet/dry penalties.
  • Your grass type set on the device — the windows are completely different for cool- and warm-season turf.
Where it falls down
  • It is a soil-temperature and moisture window, not a forecast. It cannot see the cold snap arriving on Wednesday that will kill the seedlings.
  • It does not know your cultivar, your pre-emergent schedule, your local water restrictions, or that you are away next week.
  • Fertilizer chemistry is out of scope entirely. It will tell you the soil is in the right window; it has no view on what you are about to spread.
  • The windows are broad agronomic ranges. A local extension office knows your county better than a general model does.
FIG.08

Time the rest

Multi-device Compare

“Which zone is the problem, and how far behind is it?”

Averaging two zones hides the exact problem you bought a sensor to find. This ranks every sensor on the account by health, aligns their key readings, and shows the gap.

It also works against yourself: one sensor across two periods answers “is this July worse than last July” using your own soil rather than your memory.

Three zones, one account, ranked by health
ZoneHealth Soil moisture nowLimiting factor
Back — shaded
clay · band 28–45%		 81 / 100 28.1% Light
Side strip
sand · band 12–28%		 74 / 100 14.8% Light
Front — full sun
loam · band 22–38%		 54 / 100 16.1% Moisture in band

Scroll the table sideways

Read that table twice

The side strip reads 14.8% and the front lawn 16.1% — practically the same number. But the side strip is sand, whose band starts at 12%, and the front is loam, whose band starts at 22%. The side strip is comfortable. The front lawn is nearly six points below its own refill point and is the only zone here in real trouble. Rank by the raw number and you would go and water the wrong one. This is the most common way a moisture reading gets misread, and it is exactly why the score judges every zone against its own soil rather than against a single figure.

What it reads
  • Every device on the account, each scored by the same health model
  • The latest reading from each for the headline metrics
  • Each device’s own moisture band, so zones on different soil types are judged fairly
What it gives you
  • a ranking by health score
  • the limiting factor for each zone, side by side
  • aligned curves and the gap between them
Before it can say anything
  • Two or more active sensors, or one sensor with enough history for two periods.
  • Soil type set per device, or every zone is judged against the loam band.
Where it falls down
  • It ranks; it does not diagnose. Knowing the back lawn is worst does not tell you it is shade rather than a broken head — that is what the other seven tools are for.
  • Raw %VWC across different soil types is not comparable. Sand at 20% is doing fine and clay at 20% is in trouble. The score accounts for this; the raw number in the same table does not, so read both.
  • Two sensors in the same zone will disagree slightly, and neither is wrong. Soil is not uniform.

All eight, from the first reading

Nothing above is an upgrade.

Every tool on this page is included at both prices, on every device, from the day it starts reporting. What differs is only how much history each one needs before it will commit to an answer — and each of them says so rather than guessing.

Start monitoring — $4.99/device/mo Read the 31 answers
  • Published mathsFAO-56 Hargreaves, a grass crop coefficient, least-squares fits. Named so they can be checked.
  • Published thresholds6 %VWC in two hours for a leak, 3.3 V for a battery, 15% for dry soil. The same numbers the code uses.
  • It declines to answerBelow the minimum history each tool returns a diagnostic instead of a number. Silence beats a confident guess.
  • Your data leaves tooCSV and JSON export from the first reading, whether or not you stay.