Hello! When I grow cuttings indoors under grow-light, I normally start them out around 6 hours and slowly ramp it up to 12 hour shifts to suppliment a full day's worth of light. However, if your cuttings are already used to being oudoors and in bright direct or partially indirect light, then you can just start out at around 10 to 12 hours and stay steady with that. Just be sure to follow proper instructions for your specific grow lamp when it comes to distance above plant, etc.
