Unlike smoking, when cannabis is instantly taken into circulation and dispersed throughout the brain, edibles must first pass through the digestive system. According to one study, oral intake of THC takes 30–90 minutes for effects to kick in. After 2–3 hours, these effects are at their height.  So, longest-acting edibles would stay long in your digestive system and takes time to get mixed into your bloodstream. Henceforth, the effects they produce act slowly but for longer than that of the regular weeds.