Answer: Although I suspect what you have done with the flwoering maple may be successful, it is not usually recommended. Flowering maples (Abutilon) are fairly easy to please and prefer a sunny window with moderate watering in winter, slightly moister soil during the growing season, and regular fertilizing during the growing season. A rich potting soil is also a good idea. If pinched they will remain bushy, and they will bloom more while smaller so many gardeners will root tip cuttings each year in fall or early spring. With this type of care it is potentially a winter blooming houseplant if provided enough light. The tip cuttings in fall are an ideal solution if you are limited on bright indoor space.
Brugmansias can be treated roughly the same way, as a winter flowering or conservatory plant, again if you have enough room and very bright light to keep them! Some gardeners will do cuttings with these if they do not have room to keep the parent in a bright and warm location -- or as insurance while they put the parent in a cool location. The alternative method is to do what you have done, keep them cool but not freezing (say about 45 degrees) and allow them to defoliate or cut them back. Darkness is not necessary. The risk here is in keeping them too moist, they do not need much moisture when they are not actively growing.
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