Miracle Grow is my favorite - they make spikes that go in roses and veggies and house plants.
I dilute one tablespoon of Epson Salt in a gallon of water. I sprinkle this solution on the soil at the base of my plants. Then I follow up with more water. The extra water will help the roots receive the E Salt quicker. This process puts enzymes in the soil and plants flourish with it. I use this for flowers and vegetables. Repeat every two weeks.