When winter comes and the weather gets bad, plants tend to either die or go dormant (dormant means alive but not actively growing). The ones that die are plants called annuals. Annuals are the kind of flowers you see in hanging baskets, pots, and in small flower gardens. A few examples are petunias, zinnias, and marigolds. The plants that go dormant in the wintertime are deciduous trees and perennials. Maple trees, oak trees, and weeping willows are all deciduous trees. Daylilies, daisies, cone flowers, balloon flowers, black-eyed susans, forsythias, butterfly bushes, roses, and coreopsis are all perennials.
Why do plants go dormant?
Plants like deciduous trees and perennials go dormant because the weather gets too cold. When in dormancy, the plant protects itself from the harsh climate. During this period of time, the plant will not start any new growth. If it did, the plant would become damaged by having its new growth getting killed instantly.
Why does it look like the plant is dead?
If you have gone outside and looked at your garden, it looks dead. A few of these plants might actually be done, (annuals and malnourished plants) but most of them are just in dormancy. Plants don't get bigger, produce leaves, flowers, or new stems in dormancy; therefore, it looks as if the plant is dead when it truly is not.
When do plants go dormant?
Though it looks like plants go dormant in the late fall, this is only partly true. Most plants end up starting to go dormant in the late summer when the temperature is the hottest. If it were to continue growing until late fall, (around the time of the first frost) the plant would be damaged by having its new growth die. The act of going dormant in late summer is called hardening off. Plants do this so they can become 100% dormant when the time is right.
How come plants don't poke out of the ground until after it has been warm for a while?
Even if it is warming up weather-wise, plants will wait a bit before they start growing again. There has been many occasions when it has been warm for a week or so, then freezes up again. Plants prevent early damaged by staying in the ground or not producing new growth on old stems.
I hope you have learned more about dormancy and plants in the wintertime. To conclude, I have taken a few pictures of plants in my garden that are experiencing this year's dormancy.
Author's Note: Source: http://www.gardenguides.com/130504-plants-rest-winter.html