Plants that bloom and are in active growth in the summer in our region may be affected in a variety of ways by the fall and winter.  Some plants that grow outdoors in the summer in our region are not hardy enough to survive the cold temperatures and the reduced hours of sunlight of New York area winters.  These plants, usually referred to as annuals, will die if left outside over the winter.  Different plants will die at different temperatures, though reaching the point at which we experience a hard frost is a common killer.  

Plants that can survive the winter in the New York area have various strategies for doing so.  Some gather and store energy in their roots or other underground structure (such as a bulb) and die back completely above ground until they are signaled to reemerge by factors such as warm temperatures, lengthening daylight, moisture and/or a minimum sleep period. Tulips (a bulb) and peonies (an herbaceous perennial) are examples.  Each plant has its own signal to "die back" once flowering is over and some persist into the fall while others are gone by the end of the summer.  

Other plants maintain a structure above ground throughout the year but gradually lose their leaves and stop photosynthesizing during a dormancy period, frequently the fall and winter.  Deciduous trees and shrubs such as maples and lilacs are examples.  Again, these plants each have different signals of light, temperature and moisture to induce dormancy but the brilliant autumn colors seen in our area when nights get cold and daylight hours diminish are an example of this process.  

There are some plants that continue to photosynthesize and remain in active though reduced growth during the fall and winter.  These plants retain their leaves and are considered evergreen.  Many conifers, such as yew and pine, fall into this category as do some broad leaf plants like hollies.

I hope that is helpful!

Courtesy of the NYBG Plant Information Service