Although most modern houses are kept warm during the day in winter, the temperature is often allowed to drop markedly over the night. This is a real problem for many house plants tropical origin. To not damage these plants you should put them in a place where they are protected from draughts and are not subject to wide fluctuation in temperature.
Do not leave tender plants on windowsills at night, especially if the drawn curtains close off residual warmth from the room. Also do not place plants directly above radiators or heaters that are in use. As radiators are usually places under a window, the windowsill has many hazards for indoor plants if you place them there. Too much sunlight, excessive heat from the radiators underneath and draughts trough the frame can weaken or kill your house plants that are placed on a windowsill.
To flower, indoor plants need warmth, but if the temperature is too high for the individual species, the blooms quickly fade and die. So you have to make sure you will place the plants in the right place where they will get just the amount of heat they need to bloom.
Most plants thrive in bright, filtered sunlight or in a well-lit position that is not in direct sun. plants that have variegated leaves need more light than those with plain, green leaves, but over-strong sunlight will damage the foliage.
Flowering plants need good light if they are to flower well, but excessive light can shorten the life of the blooms. Few indoor plants can tolerate direct sunlight.
Insufficient light will make your plants pale, with stunted new leaves and drawn-out or etiolated growth, with long, thin, weak stems. Also in insufficient light some variegated plants will begin to produce plain leaves and in time the mature leaves will turn yellow and fall. In the end, a weakened plant will become vulnerable to pests and diseases.
The amount of natural light in a room depends on the number, size, height and aspect of the windows. Light levels fall quickly as the distance from the window increase. In winter, there is far less natural light than in summer and some plants may need to be moved in order to receive the amount of light they need. If the plants that need to be moved are large you should use a plant trolley for this purpose.
If plants start to grow lopsidedly towards a source of light you should turn them slightly when you water them. If light levels are too low for a healthy growth you should use supplementary growing lamps, especially for plants which need a long daylight if they are to flower. Most plant need 12-14 hours of daylight per day in order to develop well.