Hi Alice,

It looks like your plant has a bacterial plant disease called leaf spot. Cut off the diseased leaves and then wash the scissors in a bleach solution. Put the plant in cool, dry location (no more than 70°) with bright indirect lightVery few houseplants should be placed in direct sun. High light refers only to bright indirect light since direct sun often burns the leaves of indoor houseplants. An area that is too hot and dry encourages Spider Mites and causes blooms to quickly fade. A northern exposure really doesn't provide enough light for high light plants. These plants need to be placed directly in front of an east-facing window, within 1-3 feet of a west-facing window, and within 5 ft. of a south facing window. A high light area has over 300 ft. candles of light.. Do not mist the plant! Water from below so leaves never get wet. Hopefully this will stop the spread of the disease to any new leaves.