Instead of purchasing multiple, or artificial/chemical, fertilizers we use Epsom salt for everything! It's available in dollar stores. A lot cheaper and simpler than the individual fertilizers for vegetables, flowers, and roses in particular.
It is used in a ratio of 1 tablespoon of Epsom salt to one gallon of water. Fill up your watering cans with it! Epsom salt is made up of magnesium and sulfate, which are both needed plant nutrients. You can start using it when sprouting your garden seeds and continue until harvest!
Great tip! Epsom salts are very inexpensive too.