Jack's Classic Bloom Booster is a good one for those who like the water-soluble kind of fertilizer. I prefer Espoma products, which are mostly or entirely organic, and have more micronutrients, and are slower-release. Flower Tone is my choice by that company, followed by Plant Tone as an all-around garden fertilizer. You could use a combination of the two...put down an application of PlantTone in the spring when you plant, and follow with occasional shots of water-soluble fertilizers.