How to avoid leaf damage with roses
When looking at the quality of roses obviously the first thing we look at is the flower. But a nice rose with damaged or dead leaves does not look attractive. Also, damaged leaves can lead to faster wilting of the flower. The leaves are the engine for transporting water and nutrients to the flower. When the engine fails the flower will not be in optimal condition. Potentially leading to the flower not opening fully and a shorter vase life.
In order for the "engine" to run smoothly it is important that the stomata function well. The stomata can be found mostly on the bottom side of the leaves. A plant/flower "breathes" through the stomata. They also regulate evaporation. Water that is evaporated through the leaves must be replenished from the vase water. This also ensures the nutrients in the vase water are taken up by the flowers. When humidity is low, which is often the case in a heated living room, the stomata close to prevent high levels of evaporation and a dried out flower as a result.
In practice the stomata do not always funtion optimally, if at all. There are multiple possible causes for this. One such cause is that the environment in a greenhouse is often optimal. The plant does not need to close its stomata causing the stomata to lose their funtionality. After harvesting the stomata will remain open and the flower will evaporate too much water. Eventually the leaves will dry out and the flower will wilt sooner. With Dutch roses this phenomenon occurs mostly during the winter. But long transport of roses with high humidity can cause similar symptoms.
This problem has proven to be very difficult to solve, despite the efforts of growers to adjust growing conditions. Tests conducted by Chrysal show that using Leafshine can have a positive effect. The evaporation of the leaves can be slowed by applying a layer of Leafshine. A positive effect on the vase life of roses was seen most evidently during winter when the heating is on and humidity inside is low.