Ask Mr. Smarty Plants

Water isn't a popular thing for plants, it is a NECESSITY. Plants, like all living things, are made of cells, and cells require water to function. Water is also necessary to carry out photosynthesis, the process by which plants make food from sunlight and water. Water is also involved in maintaining the plant's structure. When plants don't have enough water the cells collapse and the plants wilt (see the answer to a previous question for more information) and my ultimately die. Water is not only necessary in itself, it also carries vital plant nutrients (for example, nitrogen (N), phosphorus (P) and postassium (K)) to the roots of a plant.

So, you see, plants absolutely NEED water. Water taken up by plants may contain other substances like the nutrients listed above. Some people water their plants with a liquid fertilizer—water with added nutrients—and this may make the plant grow faster or larger, but the water itself is a necessity. Without water plants would die.