I've bought it to use for my houseplants, because of high % of potassium and tiny price. However it didn't dissolve in water. Is is fake of because of sand added? Have you used this fertilizer for roses or other plants? Does this work? The only reference I've found on internet is negative.
I usually do the same - I prefer professional products too, but this was some kind of emotional purchases. I've got good (I think so) fertilizer for my african violets, and I wanted something with high potash level for my streptocarpus plants. And Wilko's formulation looked good. Now I have to think about utilization of this package.