One decision, seven levers.
A comfortable plant builds leaf. Consistent mild scarcity — a deeper overnight dryback, a stronger feed, a wider day-night gap — tells it that reproduction is more urgent than expansion, and it sets fruit. None of the levers does much alone; applied together for a week they move a crop, and applied inconsistently they produce a stressed plant with nothing on it.
Balanced
| Lever | Vegetative | Derived | Generative | Why |
|---|---|---|---|---|
| Overnight dryback | 9 | 14 % | 19 | How far the substrate is allowed to dry between the last shot of the day and the first of the next. The single strongest generative lever there is. |
| Feed EC | 2.20 | 2.80 mS/cm | 3.40 | Higher feed strength lowers the water potential the roots work against, which the plant reads as scarcity. |
| Shot interval | 1,800 | 3,600 s | 5,400 | Frequent small shots keep the root zone at a steady water content, which is a comfortable, vegetative signal. |
| Runoff per shot | 12 | 20 % | 28 | Runoff flushes accumulated salts out of the root zone. Less runoff lets EC climb at the root, which is generative — up to the point where it is simply salt damage. |
| First shot after lights-on | 45 | 113 min | 180 | Delaying the first shot extends the overnight dryback into the morning, when the plant is already transpiring. |
| Day/night difference | 2.0 | 4.5 °C | 7.0 | A wider difference shortens internodes and pushes assimilate towards fruit. A narrow one stretches the plant. |
| Target VPD | 0.75 | 1.00 kPa | 1.25 | Higher deficit means faster transpiration and more calcium moved into the fruit, at the cost of stress if the roots cannot keep up. |
Every number in the derived column can be pinned in the app and the rest stay derived around it. Somebody with fifteen years in a polyhouse knows things about their own cultivar that no shipped curve does, and the correct answer to "your solver says EC 3.2 and I know this variety splits above 2.8" is to let them pin 2.8 — not to argue.
The half that makes it real
Steering is only steering if you close the loop. Three measurements do that, and all three are in the app: whether the substrate actually dried back as far as the intent asked; whether the runoff is coming off saltier than the feed, and by how much, which is the number that tells you to flush; and how many litres the crop used per mole of light, which falls days before a root problem is visible on a leaf.
The solver ships with ProEvery band on this site is a literature-derived starting point. None of them has been measured on your water, your cultivar or your polyhouse, and the variable that decides most of it — the alkalinity of what comes out of your borewell — is one this page cannot know. Validate on a small block before you commit a season.
