Product guide
Light schedules that work: photoperiod, sunrise and sunset ramps
How long the lights stay on matters as much as how bright they are. Common photoperiods by crop and stage, why gradual ramps beat a hard on/off, and how to set them up on G_Control.
Indoors, the light schedule is the plant's only clock. Get it wrong and short-day plants will not flower on time, or will drift back towards vegetative growth. Get it right and you also gain control over DLI, energy use and the working day of your team.
Common photoperiods
| Crop and stage | Light / dark (hours) |
|---|---|
| Seedlings and clones | 18/6 to 24/0 |
| Vegetative growth | 18/6 |
| Short-day crops in flower | 12/12 |
| Leafy greens and herbs | 16/8 to 18/6 |
For short-day plants, the dark period is what triggers flowering. It has to be truly dark and uninterrupted — a light switched on in the middle of the night, or a leak around a door, can be enough to disturb it.
Why ramp the lights up and down
Outdoors, light rises over an hour or more. Indoors, a hard switch takes the canopy from zero to full intensity in an instant. A sunrise and sunset ramp brings intensity up and down gradually instead.
- Gentler on plants. Stomata and leaf temperature adjust gradually instead of all at once.
- Gentler on the room. Climate equipment sees a gradual heat load instead of a step, so temperature and humidity swing less.
- Gentler on the electrical system. Fixtures ramp together instead of every driver starting at once.
Ramps do reduce the total light slightly. A 30-minute ramp at each end of a 12-hour day removes about 4% of the DLI, so some growers extend the photoperiod by the same time when the crop allows it. For short-day flowering crops, keep the total, including ramps, within the 12-hour window.
Setting it up on G_Control
G_Control drives up to 100 fixtures on each of its two RS485 groups. White and red channels can follow their own schedules, ready-made scene modes (Flower 1–4, Bloom 1–2) cover common stages, and sunrise and sunset ramps of 1 to 60 minutes run automatically. If a room overheats, G_Control dims the lights first and only switches them off above the shutdown temperature.
- Connect the fixtures to the controller's RS485 groups.
- Set the lights-on and lights-off times, then the sunrise and sunset duration.
- Pick a scene mode or adjust spectrum and intensity per channel.
- Check the history the next day to confirm the room followed the plan.
With the controller connected to Big G plus, you can check and adjust schedules from your phone, and every change is visible to the rest of the team.
Planning a room?
Send us the room size and the crop. Our engineers will suggest a lighting and control layout that fits.
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