I'm having a really hard time understanding how to use the fertilizer effectively. The in game description is very vague and my google searches have turned up a lot of guesses. Is there anyone who has used it enough to provide some guidance on how to use it and what to expect?
Also, is it true that there is a limit to how many flowers you can have in your town?
If you plant it next to a flower pair, you increase your chances of getting a hybrid. I have great luck using it with Roses, Pansies, and most tulips. I have varying success with it on Cosmos and I've found that for orange lillies and pink tulips, it rarely ever works for me. So if I have five purple tulips in an X pattern, I plant it next to the middle tulip. Then water the flowers.
You can also use it next to a town's native fruit tree to increase the chance of getting a perfect fruit. I have not tried this though since I have a whole orchard of perfect fruit trees.