In this experiment the effect of light intensity (photosynthetic photon flux density, PPFD) and cutting size (10 and 7 cm) was investigated during five weeks rooting of hibiscus (Hibiscus rosa-sinensis L. ‘Adonicus Yellow’). The light regimes included three constant PPFD: 16, 76 and 151 µmol m⁻² s⁻¹; and three changing PPFD after two weeks: 16 → 76, 16 → 151 and 76 → 151 µmol m⁻² s⁻¹. The light intensity has a dual effect, promoting photosynthesis and carbohydrate production, but also water loss through transpiration with the potential for desiccating the cutting. The treatments starting with 16 µmol m⁻² s⁻¹ insufficiently supported the rooting process, illustrated by the lack shoot growth after two weeks. Within each treatment type (constant or changing PPFD) the root formation was linearly correlated to the total light integral for the propagation period (r² = 0.835–1.000) for respective cutting size. The changing PPFD treatments showed the strongest response to increasing light integral with the [76 → 151] treatment producing most roots for both cutting sizes, despite the constant 151 µmol m⁻² s⁻¹ having the highest total light integral. This indicates that conserving water is of crucial importance before root emergence in the third week of rooting. The 7 cm cuttings produced more root biomass and had higher root:shoot ratio than the 10 cm cuttings. The 7 cm cuttings had higher rates of photosynthesis one week after rooting, probably due to higher sink demand from the growing roots and mobilised more soluble sugars from the leaves. The rooting process takes five weeks and does not demand high light, so the results are promising for moving propagation of hibiscus from the greenhouse to a vertical production system based on light emitting diodes (LEDs) to save production area for final production.