Why do plants stop growing in the winter? The winter in the northeast the past few months was very mild.?

Question

The winter in the Northeast this past winter was very mild and didn't see a lot of cold days. In fact, there were a lot of days when the weather was in the 70s and some in the 80s but the plants still weren't growing. Why is this? The ground was warm, people were out playing golf but I didn't have to cut my lawn.
What makes the grass stop growing? Is it the "angle" of the sun? The ground temperature? The "enzymes"? Some kind of genetic hibernation function triggered by the first front or a couple of days of cold weather?

Answer 1

There is a hibernation program that kick in when the number of hours of sunlight hits a threshold. A similar program causes tree leaves to stop producing chlorophyll and fall off.

Answer 2

The answer is in your question itself. During winter they hardly get sun light, which a must for photosynthesis. Hence they shed all leaves and stop growing, to conserve.

Answer 3

Many flowers are not triggered by temperature but by daylength, so the only way to make them flower in winter is to give them artificial sunlight when outside it is dark.

Answer 4

Even if it does not freeze, deciduous plants cycle through the year based on triggers from hours and intensity of sunlight.

Answer 5

its natural for them to shut down in winter to conserve energy because the sun's rays arent strong enough for photosynthesis to happen. its been engraved into it that its very hard to change because of a little difference.
enzymes and phytohormones cause it.