Propagation lights exist because a cutting cannot use a flowering fixture. It has no roots, so it cannot take up water fast enough to cope with high light intensity – put a seedling under a 600W and it wilts, bleaches or simply stalls.
What propagation actually needs
Low intensity. Roughly 100-300 µmol/m²/s, against 800-1,000 in flower.
Long photoperiod. 18/6 or even 24/0 for cuttings. Duration, not intensity, is what drives early growth.
Blue-weighted spectrum to keep growth short and stocky rather than stretched.
Almost no heat. A propagator is already warm and humid; a hot lamp above it cooks the dome.
The options
Type
Notes
T5 fluorescent bars
The traditional choice. Even, cool, cheap. 2ft and 4ft, 2 to 8 tubes.
CFL
Cheapest way in. Fine for a handful of cuttings on a shelf.
Low-wattage LED bars
More efficient and longer lived. Now the sensible default.
A dimmable main fixture
Works if you can genuinely dim to 15-20% and hang it high.
Hanging height
T5 and CFL run cool enough to sit 15-30cm above the canopy. LED bars want more – 30-45cm at low output. If cuttings are stretching, the light is too far away or too weak; if the tips are bleaching or curling, it is too close.
We are a hydroponics shop in Croydon and we propagate every week. Tell us your tray size and we will match the light. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.
