Roses like tomatoes require a great deal of minerals in order for them to produce their flowers. In the tomatoes cases we want the minerals because we will be eating it and in the roses case, we want the minerals so that the Brix level will be high enough to deter pests.
The Higher the Brix level the Higher the Mineral Levels. Also the higher the Brix level the higher the Carbohydrates. What is better known about Brix is that it is a measurement of sugars in the plant. The higher the Brix the higher the sugar level. Look up Brix and you will see that wine producers use it as do beer makers. Beer is fermented sugars.
Here is the Brix level chart I have developed for roses:
Brix and Roses Chart
The basic idea is to use a refractometer to get readings from say your roses. The Brix readings will help you to determine if what you are doing is working or not. It wont take long for you to use a refractometer like an old pro and it wont be long before your roses start to show it!