How does light actually trigger different kinds of plant growth? What does this answer mean for the placement of plants in windows or indoors?
Flowering plants are all defined by light exposure. Some plants (short-day) will only flower when exposed to light for a shorter period of time than a critical value. These are the species that flower in the fall, when day lengths become shorter over time. Plants that flower in the spring (long-day) are the opposite. They will only flower when exposed to sunlight for a period of time longer than a critical value.
When plants are indoors, it is crucial for light exposure to mimic natural conditions for natural flowering cycles to occur. Often, plants will be exposed to more light than usual when placed inside due to the use of light bulbs at night. Short-day plants will not flower when this is the case, while long-day plants will flower more often. Plants placed by windows will experience natural light cycles and therefore will experience natural flowering cycles.