Select a fertilizer that is appropriate for the plant you are growing to get optimal performance in the container. Use citrus fertilizer for citrus plants, and blueberry/rhododendron fertilizer for vacciniums (blueberry, huckleberry, lingonberry and cranberry). For Bananas, encourage lots of vigorous growth initially with a foliage supportive formula that has a high nitrogen content, then switch to a formula that is higher in phosphorous (a bloom fertilizer) to encourage flower and fruit development. Bamboo, lemon grass, and sugar leaf all benefit from higher nitrogen fertilizers once they are actively growing. Many fertilizers either list what kinds of plants they are formulated for, or what kind of growth they support (such as foliage vs. fruiting).
Slow release fertilizers: If you prefer not to mix liquid fertilizer in when you are watering, consider spreading a long lasting slow release granular or pelleted fertilizer on the soil surface (or you could have mixed some in when you re-potted last winter). Most slow release fertilizers depend on temperature to regulate nutrient release. Don’t expect much performance from the fertilizer until the weather has warmed up. Choose a long release period (such as 6-9 month) to ensure your plants continue to grow well through the summer. Use an appropriate formulation for what you are growing. Fruiting plants need a different balance of nutrients than foliage plants.