Three ingredients help flowers grow the best and grow as fast as they can: Food, water and light. Each type of flower requires a different amount of each of the three ingredients, and in some cases, even a different type of those ingredients. Flowers will grow at their own rate, but with the proper amount of ingredients, the rate can be sped up to the fastest rate that the particular flower will grow.
Fertilizers fall into two categories: Organic and chemical. Once you choose which type of fertilizer you want to use, you must determine which fertilizer is the best for the type of plant you are growing. Some plants need more nitrogen and some need more phosphorus. Some plants (usually shrubs and trees) need a phosphorus-based fertilizer when first planted so that the root system becomes established. After establishment, you can use a fertilizer designed for that plant (i.e. rose fertilizer or palm fertilizer) or a good, all-around fertilizer.
Water-soluble fertilizers for flowers and vegetables are the best fertilizers to use for annuals and perennials that are not trees or shrubs. Flowering-shrub and -tree fertilizer is the best all-around fertilizer for shrubs and trees.
Some plants require lots of light, some require a medium amount of light, and some require very little light. If a plant that requires full sun (more than eight hours of continuous sunlight) is only given partial sun, the plant will not thrive and may even die. If the plant prefers shade, but is planted in an area that gets full sun, it will also not thrive and possibly die. A nursery employee or the information that is provided with the plant provides you, the grower, with the proper amount of light for the type of plant you buy.
Like light and food, plants need the proper amount of water. If the flowers and plants get too little to too much water, they will not grow fast, may not bloom, and may even die. The nursery employee or the information that comes with the plant provides you with information regarding watering, though most plants, unless they are plants that prefer dry living conditions, take at least an inch of water per week.