how does a plant keep itself alive in winter??

Question

its cholophylls aren't working .
how are some plants ever-green (like olives)

Answer 1

Water is the problem in cold. Water expands when it freezes so the plant has to protect itself from this. If a plant cell freezes, it does what a frozen water pipe does: it ruptures.
Plants use two methods to become dormant so they prevent the damage. They stop all reactions that require water. This means they stop growth, they store food for spring start up, then they use plant antifreeze to avoid damage. They do this when the day gets short before the first frost date usually.
If the region gets well below freezing the plant may do more to protect itself. They also move water out of cells leaving the substances that tolerate cold without freezing inside. Water sits between cells frozen but not breaking the cell open. In this extreme form they also count the number of hours they spend below freezing. Plants in this phase can not wake up til enough cold time has passed so if a few warms hours happen they do not respond.
Olives and other warm climate plants do not have these protective means so if they freeze they will suffer die back. Some plants expect and allow die back of all above surface structures protecting only the root and crown to regrow from.

Answer 2

Senescence is peculiar to deciduous plants only and plant energy and storage is usually held in roots or tubers even in evergreens. Some photosynthesis still occurs, but at much lower levels in this range of plants. The reason deciduous plants shed their leaves is because it would require much more energy than necessary to withstand winter during diminished sunlight hours.

Answer 3

Perhaps you could have some small compact flourescent lights near the plants on a timer that serves to continue the light cycle after sunset for a few more hours during fall and winter