Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
Inputs
12 parameters · live recalculation on every change
M²
1m²
50m² default
1000m²
/DAY
1/day
4/day default
24/day
L/H
0.5L/h
2L/h default
20L/h
Pro Settings — Lab Controls
0.5
1 default
2
°C
10°C
20°C default
35°C
MS/CM
0.5mS/cm
1.8mS/cm default
4mS/cm
Advanced Settings — Deterministic Corrections
%
5%
20% default
50%
L
1L
10L default
100L
1
10 default
100
%
5%
20% default
50%
Deterministic model
12 inputs · 10 outputs
Runs 100% in your browser
This is a deterministic model: the same inputs always produce the same outputs, calculated entirely in your browser with nothing sent to any server. It is a planning aid — not a quote, not a dosing instruction, and not a yield forecast. Treat every line as a working estimate and validate it against your own prices and measurements.
It models one system: An irrigation schedule calculator that starts from the dryback you want to steer: drip timer minutes = substrate volume × dryback ÷ (flow rate ÷ 60 × emitters), scaled by plant stage, VPD factor and root-zone temperature, against the field capacity of your medium — coco 75%, rockwool 80%, soil 45%. The drip irrigation calculator then prints events per day, the runoff that shot actually makes, litres per day, substrate moisture, and the EC drift those numbers buy, inside a green—yellow—red safety band.
What the Irrigation Timer Calculator — Drip, Schedule & Dryback Blueprint returns
The engine computes 10 outputs from your 12 inputs. The headline number is Irrigation Time (min), alongside Events / Day, Runoff Actual, Dryback Actual. Every output updates live as you change a parameter.
What it does not do
Outputs depend on the inputs and assumptions shown here. Confirm relevant measurements and local conditions before acting.
STEP 01
Pick the medium and the stage: field capacity by substrate — coco 75%, rockwool 80%, soil 45%, perlite 35%, clay 50% — decides the water bank the dryback rolls against.
STEP 02
Set the dryback target: the percent of that bank you want transpired between events, 10–30% for the working band, higher with higher EC for generative steering.
STEP 03
Compute irrigation time: substrate litres × dryback ÷ (flow L/h ÷ 60 × emitters), scaled by stage (seedling 0.5, veg 0.8, flower 1.0, fruit 1.2), VPD factor and root heat (+2% per °C over 20).
STEP 04
Adjust events per day: base frequency × VPD × (1 + 0.05(T − 20)) — a dry hot room waters more often without a manual change.
STEP 05
Close the loop on runoff and moisture: runoff = (shot − substrate × (1 − dryback) × FC) ÷ shot; moisture = 100 − dryback actual — no drainage means every fed ion stays in the pot.
STEP 06
Read the safety band: dryback 10–30 %, runoff 15–25 %, moisture 50–75 % green; the red edges are dryback <5 or >45, runoff <10 or >35, moisture <40 or >85 — and the EC drift line tells you what no-runoff is really costing.
T = \frac{V_s \cdot d}{\frac{q}{60} \cdot n} \cdot f_{stage} \cdot f_{vpd} \cdot f_{temp}
Irrigation timer minutes — the dryback shot divided by drip delivery
f_d = f_b \cdot f_{vpd} \cdot \left(1 + 0.05\,(T_r - 20)\right)
Events per day — base frequency adjusted by VPD and root heat
R = \frac{V_{shot} - V_s(1 - d)\,FC}{V_{shot}} \cdot 100
Runoff — the drainage your shot actually produces
d_{act} = d \cdot \left(1 + (1 - f_{vpd}) \cdot 0.2\right)
Actual dryback — target corrected for how thirsty the air is
V_{day} = \frac{T}{60} \cdot q \cdot n \cdot f_d
Water per day — shots summed across the day
M = 100 - d_{act}
Substrate moisture — what the sensor should read after dryback
\Delta EC = EC_{t} \cdot \left(1 - \frac{R}{100}\right) \cdot 0.1
EC drift — the salt your runoff leaves behind
d\,10{-}30,\ R\,15{-}25,\ M\,50{-}75 \text{ GREEN} \ \text{vs} \ \text{RED: } d<5 \,|\, d>45 \,|\, R<10 \,|\, R>35 \,|\, M<40 \,|\, M>85
Safety bands — dryback, runoff and moisture
Field capacity by substrate is the locked baseline: coco 75%, rockwool 80%, soil 45%, perlite 35%, clay 50% — the archived engine held a comparable per-medium water-holding table and sized shot volume off it.
Irrigation time on the defaults — 10 L of coco, 20% dryback, ten 2 L/h emitters, flower stage — lands 6.0 minutes; flip the stage to seedling (0.5) and it halves to 3.0 minutes exactly, which is why the seedling line reads short.
Honest runoff: a 6-minute shot pours 2.0 L into 10 L of dry coco that can hold back 6.0 L — the event never drains, so runoff real is 0% and the safety band trips red on the runoff edge. Hitting 15–25% drainage needs a shot near the storage (roughly 7–8 L), a proper water-on-water event, not a dry pulse.
Dryback and moisture move together by construction: actual dryback = target × (1 + (1 − VPD) × 0.2); moisture = 100 − dryback actual. At the 20% target moisture reads 80%, a touch past the 75% top of the green band.
EC drift is the honest consequence of zero runoff: ΔEC = EC target × (1 − runoff ÷ 100) × 0.1, so with no drainage at a 1.8 mS feed, salts accumulate ~0.18 mS/day — the runoften 15–25% keeps drift near zero and this panel shows exactly why you flush.
The recommended-shot arm uses your runoff target: shot needed = substrate × (1 − dryback) × FC ÷ (1 − runoff target ÷ 100) — wire your own 15–25% to see the gap between what your timer fires today and what the deliberate drainage event looks like.
- Irrigation time: T = substrate × dryback ÷ (flow ÷ 60 × emitters), scaled by stage, VPD and root temperature — the archived timer divided shot size by dripper rate to turn a dryback pulse into timer seconds; this arm resolves the same rule into minutes on your zone.
- Field capacity by medium: coco 75%, rockwool 80%, soil 45%, perlite 35%, clay 50% — the archived engine held a per-medium water-holding table so shot size followed the medium; the locked table here is that bank the dryback rolls against.
- Frequency: events/day = base × VPD × (1 + 0.05(T − 20)) — the archived cycle count came from a per-medium base adjusted by stage and environment; this arm folds the environment into the VPD factor and root heat so a dry hot room waters more without a manual change.
- Runoff: R = (shot − substrate × (1 − dryback) × FC) ÷ shot — a drip event makes drainage only after the medium can hold no more; the archived drip guide tuned events toward a 10–20% runoff flush and this arm reports the drainage your shot actually produces.
- Dryback steering: actual = target × (1 + (1 − VPD) × 0.2); moisture = 100 − dryback — the archived dryback discipline used larger drybacks with higher EC to send the generative signal; this arm keeps the actual dryback honest against what the air really draws.
- EC drift: ΔEC = EC target × (1 − runoff ÷ 100) × 0.1 — no runoff means every fed ion stays in the pot; the archived nutrient discipline tied salt buildup to the drainage fraction, so the drift line here rises exactly when the runoff line falls.
This model combines the earlier Irrigation-timer, Watering-schedule-calculator, Drip-irrigation-calculator models.
Q1: How often should I water hydroponics? ▾
There is no universal interval: the events-per-day line is base frequency × VPD factor × (1 + 0.05 × (root temperature − 20)). The medium decides the volume and the air decides the cadence — coco at 75% field capacity with a 20% dryback target and a comfortable 1.0 VPD runs about 4 events a day, while a hot dry room at 1.3 VPD and 28 °C roots pushes that toward 6. The real arbiter is the dryback your substrate shows between shots: if the moisture reading falls out of the 50–75% band, adjust frequency before you adjust flow.
Q2: Drip irrigation timer calculator: how do I set the minutes per event? ▾
Set minutes, for the shot: T = substrate litres × dryback target ÷ (emitter flow ÷ 60 × emitters), scaled by stage, VPD and root temperature. Worked example: 10 L of coco, 20% dryback, ten 2 L/h emitters at flower gives 10 × 0.20 ÷ (2 ÷ 60 × 10) × 1.0 × 1.0 = 6.0 minutes. Every scheduled shot pours 2.0 L across the zone — and because that is dry-substrate refill, it drains nothing. If you want a real 15–25% runoff flush, the panel recomputes the shot your runoff target needs before you trust the drip line.
Q3: Dryback target calculator hydroponics: what dryback should I steer? ▾
Dryback is the percent of the medium\u2019s water transpired between events, and it is your growth steering lever. The engine\u2019s working green band is 10–30%; bigger drybacks with a higher EC feed send the generative signal — heavy fruiting, more essential oil — and light drybacks keep the crop vegetative. The stage factor encodes it: seedling 0.5, vegetative 0.8, flower 1.0, fruit 1.2, so the same drip line fires longer toward the finish. Stay under the 45% red edge: moisture below 40% is tissue-stress territory no matter what the target says.
Q4: Irrigation schedule calculator: how do I split the deliveries across the day? ▾
Split the total by events, then by the clock: water per day = minutes ÷ 60 × flow × emitters × frequency keeps the daily volume honest, and 24 ÷ events gives the spacing window — 4 events mean a fire roughly every 6 hours from lights on. The VPD-adjusted frequency output is what the air demands (frequency × VPD factor), so a room that climbs through the day pushes more of the volume into the hot stretch. The archived engine ran a single irrigation band from about 06:00; this arm simply spaces the same total across the light period.
Q5: How to calculate irrigation time and runoff for drip systems? ▾
Two equations run the whole answer. Irrigation time: minutes = substrate × dryback ÷ (flow ÷ 60 × emitters) × stage × VPD × temperature factor. Runoff: R = (shot − substrate × (1 − dryback) × field capacity) ÷ shot × 100. Take 10 L rockwool (80% FC) at 20% dryback: the medium can retain 6.4 L, so every shot beneath that drains nothing and R clamps to 0%, while a 7.5 L shot returns R ≈ 15%. Then the EC drift line converts the runoff you actually make into salt: ΔEC = EC target × (1 − R ÷ 100) × 0.1.
Q6: What is dryback in hydroponics, and how does it relate to substrate moisture? ▾
Dryback is the percentage of the substrate\u2019s water the plant transpires out between irrigation events. It is measured against field capacity — what the medium can hold: coco 75%, rockwool 80%, soil 45%, perlite 35%, clay 50%. Moisture is its mirror image by construction: moisture = 100 − actual dryback. A 20% dryback target therefore reads 80% moisture on your sensor, which is how the tool reconciles the steering target (dryback) with the probe you actually read (moisture) — and why the green moisture band of 50–75% is the same decision as a dryback between 25 and 50%.