A clean flip protects yield and quality. Use photoperiod discipline, staged intensity, spectrum emphasis, and gentle ramps to move plants from veg to flower without stress.
TL;DR: Switch to 12/12, lower hang height or dim up gradually, prioritize red/far-red in flower, and consider a sunrise/sunset ramp on lights-on/off.
1) Lock Your Photoperiod First
For photoperiod cultivars, the classic 12 hours light / 12 hours dark reliably initiates flowering. Keep the dark period uninterrupted to avoid delays or re-veg. If you’re coming from veg at 18/6, make the change cleanly at the next lights-off and hold it steady thereafter.
Why 12/12? See FloraFlex’s primer on flowering photoperiods. Read more.
2) Stage Your Intensity (PPFD) and Hang Height
Early flower responds best to gentle step-ups in intensity. Instead of jumping straight to full power, add 5–10% output (or a few centimeters of hang-height change) every couple of days while watching leaf posture and runoff EC. This reduces shock and helps you find the ceiling for each cultivar.
Most pro fixtures support 0–10V dimming, letting you ramp predictably across rooms and weeks. FloraFlex 700W Full-Spectrum and Under-Canopy 3-Bar 360W both list 0–10V dimming for smooth control.
3) Use Sunrise/Sunset Ramps to Reduce Stress
A short sunrise/sunset dimming period at lights-on/off softens transitions, limiting sudden PPFD spikes that can cause leaf droop or transient stomatal closure. Schedule a 10–20 minute ramp when possible.
Tip: FloraFlex’s Master Lighting Controller supports sunrise/sunset and multi-zone 0–10V control for consistent room-wide ramps.
4) Nudge the Spectrum Toward Red/Far-Red in Flower
As you transition to bloom, emphasize red (~660 nm) and include far-red (~730 nm) where appropriate. These wavelengths support flowering dynamics and can improve lower-canopy development when used thoughtfully.
Background reading on spectrum needs in flower: spectrum in flowering and far-red under-canopy overview.
5) Support the Lower Canopy (Weeks 2–5)
Where plant size and density justify it, under-canopy bars can help the lower branches keep pace with tops. Add them after stretch stabilizes, align output with your dry-back targets, and verify uniformity across benches.
- Entry footprint: 3-Bar 360W (4×4–4×6)
- Larger tables: 6-Bar 720W (4×8–4×12)
Quick Flip Checklist
- Switch to 12/12 and protect the dark period.
- Step intensity in 5–10% increments; track leaf posture and runoff.
- Enable a 10–20 min sunrise/sunset ramp via controller.
- Prioritize red/far-red emphasis during flower.
- Consider under-canopy support once stretch settles.
