There is no defined breeding season for Parrotlets kept indoors. I have had pairs produce in every month of the year. Although there are two windows in my current indoor birdroom, I use full spectrum lighting at the rear of each cage unit. The lights come on at 8am and go off at 11pm. Although the room is air-conditioned, in the summer months the daytime temperature never falls below 80 . In warm climates where the birds are housed outdoors year round they will generally breed in all but the hottest months.