Photosynthesis happens when the green leaves produce nutrients (carbohydrates). When there is sunlight and chlorophyll present, the leaves convert carbon dioxide (CO2) and water (H2O) into carbohydrates (C6H12O6). No Atkins diet for these guys!! These carbohydrates are simple sugars – that’s why sap tastes slightly sweet! Oxygen (O2) is left over and released into the atmosphere. Without green plants getting rid of excess oxygen – we wouldn’t have breathable air on this planet.

Once the carbohydrates are created in the leaves, they are moved around in the plant and broken up into other compounds by enzymes within the cells. This releases chemical energy which is used in many other cell processes. Water and carbon dioxide are also released. The rate of respiration depends on temperature and the availability of oxygen and the simple carbohydrates. Respiration speeds up when it is warm and slows way down when it gets cold. But - - it never stops! The plant is continually feeding off of the chemical energy created during respiration. Parts of the plant that are cut off or harvested – like a long-stemmed rose – still respire!

So – photosynthesis makes the food (the simple carbohydrates), and respiration consumes the food. This goes on in a cycle. The photosynthesis part happens in the day when there is light and it peaks during midday and ceases at night. Meanwhile, respiration occurs 24/7, at variable rates depending on temperature. In order for the bush to grow and develop normally, photosynthesis must occur at a rate that greatly exceeds the rate of respiration.

Water moves through the plant, going from an area of high water concentration (like the roots) to areas of low water concentration (like the leaves and stem tips). Water evaporates from the leaves through the stomata on the underside of the leaves. A continuous flowing column of water is maintained in the xylem from root to stomata, as long as there is water in the soil and the stomata are open. Transpiration helps to cool the rose bush on hot days, and transports minerals and organic compound from the roots to the leaves. It stops at night when the stomata close up.

Your rose is a living, breathing (in the sense that oxygen and carbon dioxide are exchanged during the life processes) food producing machine that relies on YOU to supply water and adequate minerals and organic compounds to the roots so its leaves can do their job of producing energy for the life processes of the plant. You are responsible – after all, your rose can’t borrow the keys and drive to the nursery to shop for nutrients!