All fertilizer bottles have a breakdown of the nutrients it contains.
N stands for Nitrogen- A higher number is for the green growth of a plant for example 24-8-4. Most beneficial are plants that do not flower, for example: kale, lettuce, grasses and lawns etc which need more to produce lush top growth.
P stands for Phosphorus- A higher number is for the flowering of the plant. For example 8-24-8 Plants needing this fertilizer are for example tomatoes, squash, daylilies, annuals etc. Select a fertilizer with a higher number to ensure lots of blooms.
K stands for Potassium- This number is for the root development and general vigor of the plant.