While there are plenty of reasons to assume that GRODAN stone wool is a superior growing media, what better way to confirm this than through experimentation?
When you run a test to compare two (or more) types of growing media, you need to make sure all growing conditions are the same. All plants should be exposed to the same conditions: light, temperature, humidity, nutrient, etc.
One variable that you will likely need to adjust is the amount of water given to the various mediums, as different media have dissimilar water holding capacities. Both the amount of water and the frequency of watering need to be adjusted to the individual medium. An example would be comparing clay pellets in a 4” pot with a 4” GRODAN block; clay pellets would need continuous watering (or at least very frequent), whereas GRODAN requires only intermittent watering.
Take a minute to view the experiments outlined on this website and see for yourself why serious growers choose GRODAN.