Answer: Plants are naturally adapted to their native range environment, and so many plants do require a certain amount of chilling in order to flower and produce fruit. An example of a plant that needs at least some cold each year is the apple. You could not grow apples in a tropical climate because it is not cold enough to provide the necessary chilling. Conversely, there are plants that will not survive cold temperatures, or that will tolerate it only to a certain temperature.
There is actually a map showing winter hardiness zones for plants. You might like to look at it and read the explanation of how it was developed and what it means to plants (and gardeners) at
With regard to the winter weather in New York contrasted with weather in Maryland, there are many reasons why there would be such a variation. Generally, the further the distance from the equator, the more marked the seasonal differences are and the more temperate the climate will be. New York is hundreds of miles north of Maryland and therefore would be expected to be colder.
Climate also depends on other many other factors such as prevailing wind patterns and proximity to bodies of water. These types of factors explain why Buffalo has so much snow while Portland Oregon does not, and why it is so much colder in upper New York state than it is in, say, Scandinavia.
Microclimates are also important. Microclimates develop within cities, neighborhoods, and even your own yard due to elevation (including low spots), wind exposure, and protection from tall trees or buildings.
Weather and climate are fascinating stuff! I hope this answers your question.
Q&A Library Searching Tips