When you buy fresh flowers from a florist or a grocery store, it typically comes with a little packet of plant nutrients. These nutrients contain plant food including sugar and citric acid as well as additives that encourage a plant to take in water and flourish for a longer period of time before wilting. You can achieve the same effect at home with cut flowers by mixing salt into the water.
Since ancient times, salt has been known for its antibacterial properties. Salt water, known as brine, has been used to preserve food through pickling since Roman times. Salt water kills bacteria through osmotic pressure. When a bacterium is exposed to a salt water environment, the concentration of water in the saline solution is less than in the bacterium. This causes water to migrate out of the bacterium through its permeable cell wall, and dehydrates it.
Encourages Water Uptake
The stems of a cut flower are like a soda straw. Water is drawn in at the base of the stem and feeds the plant at the top of the stem. Like bacteria, the cells of plants may become dehydrated through osmotic pressure. However, in a plant, the reaction is very different than in a bacterium. A plant that is dehydrated will absorb water through the stem much more quickly than one that has sufficient water. Because of this, alternating filling your vase with a saline solution and fresh water will cause the plant to take in more fresh water.
Feeds the Flower
Soft water or water that has been distilled is water that has had the nutrients that your plant or cut flower may need removed from it. Adding salt to soft water can return many of these nutrients back to the water. Salt contains potassium, a nutrient that is known in fertilizers as "potash." The term potash came from the early practice of leaching potassium from wood ashes and then evaporating the water in large pots. Additionally, two major ingredients in Epsom salts are magnesium and sulfur. According to the Epsom salt council, magnesium and sulfur are key ingredients when it comes to producing chlorophyll which a plant uses for photosynthesis. Magnesium and sulfur also work together to help a plant produce and process primary nutrients: sulfur contributes to the creation of nitrogen and phosphorous, while magnesium aids a plant in absorbing these nutrients.