Water is a critical part of life as we know it. All living organisms require water to survive. You and me as well as your houseplants long for water in order to carry out some essential processes in our bodies and stems. Water is used in many different ways but we can narrow it down to four categories. After we talk about these four categories we will talk about your plant babies, how they use water and we sometimes abuse them with water.
Category #1: Solvent
Water is made up of two Hydrogen ions and one Oxygen ion. The hydrogen ions are positively charged while the oxygen ions are negatively charged. This means that a molecule of water shares its hydrogen ions readily with other molecules containing oxygen. H2O attracts both positive and negative ions due to the charge of its molecules of oxygen and hydrogen. Positive ions are always attracted to the oxygen molecules and negative ions are always attracted to the hydrogen ions. This affinity for sharing ions makes water very good at dissolving compounds. An example of this would be when water is used to break down food into glucose which can be used for energy. A plant does this during photosynthesis.
Category #2: Temperature Buffer
There are a vast array of chemical reactions that take places in the cells which are temperature sensitive. Enzymes that are catalysts for chemical reactions are heat-sensitive and will only do their job if the temperature is just right. Wate is used to help an organism regulate temperature. It takes a lot of energy in the form of heat to raise the temperature of water. A large quantity of heat is absorbed by water without affecting the temperature of the organism which allows chemical reactions to proceed uninhibited.
Category #3: Metabolite
The total of chemical reactions occurring within an organism is called metabolism. Water is a chemical involved in reactions within an organism and can be labeled as a metabolite. During photosynthesis, water splits into its hydrogen and oxygen atoms. These two atoms are used or released. They hydrogen is used in a chemical reaction to produce glucose which feeds the plant. In animals water is used in respiration. Water helps split atoms and move waste products out of the body as a part of the respiration cycle.
Category #4: Living Environment
A bunch of organisms need water to survive. Fish for example need water to breathe. They utilize water to absorb the dissolved oxygen and without water they could not access the oxygen needed to breathe. As we have discovered, water is a good temperature buffer. This means that organisms can live in water even if the air temperature fluctuates drastically. Because water takes a lot of heat to change its temperature, the water allows organisms an environment with a stable temperature.
So how do plants use water and what happens when I don’t use water the right way?
The chemical reaction plants use sunlight to create energy for themselves is called photosynthesis. Water is one reactant and carbon dioxide is the other during this process. These two compounds react in the presence of sunlight to generate glucose and oxygen which the plant uses for energy and expels respectively. Water is utilized by the plant to transport minerals around the plant almost in the same way blood moves in our bodies. Water is responsible for Turgor pressure in the plant. This is almost like a hydraulic system in the body of the plant. When Turgor pressure is low the plant becomes soft and wilts. When the Turgor pressure is adequate the plant stands tall and springs back when moved. Water also evaporates from the leaves of the plant allowing the plant to stay cool.
Water is absorbed through the roots of most plants. In the root the water moves into the xylem which is like a highway system to the rest of the plant. When water reaches the leaves of a plant it exits through pore-like openings in the leaves called stomata. Sometimes we see small drops of water on the tips of the leaves of our plants. This is water leaving the stomata. When the summer comes and it heats up the plant loses water out of its stomata at a faster rate. This is called transpiration. If the humidity is higher the evaporation is slower because the water can not move into the atmosphere as easily because there is already lots of water in the air. Plants that enjoy a wetter environment or need lots of water will benefit from a more humid environment because it loses water more slowly.
When roots do not have access to oxygen, like when they sit in soggy soil for too long, they begin to die. The longer the roots go without oxygen the more damage is done. If a root dies it is no longer capable of carrying water, oxygen, and nutrients to the rest of the plant via the xylem. Waterlogged roots are more susceptible to fungi that cause root rot and can kill plants. If a plant has rotten roots it is incapable of carrying water to the rest of the plant. If you are not aware that your roots are rotten then from the top your plant may look like it needs more water. The roots are not functioning well after all. Once root rot occurs there is no way to reverse it.
The best way to prevent over watering is to use your finger, a trowel, or a moisture reader to check the soil deeper in the pot. The soil at the top of the pot can be deceptive. Some find it helpful to lift the pot in order to judge its water content. A heavy pot means lots of moisture and a light pot means some water is needed. It will take some time to learn each plant and their needs.
Water is abundant on this planet and works in many aspects of life here. Our plants love water but too much can damage them long term. Water is essential to the health of every plant. That is why it is so important for us to master watering or plants well. It is ok to make mistakes as long as we learn from them!