Choosing flower fertilizer that will make your flowers healthy and beautiful begins with understanding plant nutrients. Plants need nutrients, and fertilizer is essentially food for your flowers. The best flower fertilizer will provide your garden with nutrients, which is particularly important in soils that are not nutrient-rich, such as clay or sand.
The three primary plant nutrients are nitrogen, phosphorus, and potassium, and plants need them in higher amounts than other nutrients. Nitrogen is important for growth, especially for leafy plants and grass. Phosphorus is beneficial for bulbs and perennials because it strengthens the roots and increases the size of the flowers’ blooms. Potassium helps with the general health and strength of your flowers. These primary nutrients sometimes are called macronutrients.
Fertilizer manufacturers usually include the levels of the macronutrients on product labels. The amounts of each nutrient often appears as a chain of numbers, such as 5-15-20. Nitrogen levels are represented by the first number, and the second and third numbers are the amounts of phosphorus and potassium, respectively. The best flower fertilizer will have high levels of potassium, because the nutrient creates bigger and brighter blooms. A 10-10-17 mix is popular among flower garden enthusiasts because of the high potassium ratio.
In addition to macronutrients, flower fertilizer contains secondary nutrients and trace elements. The secondary nutrients, also known as micronutrients, are calcium, sulfur, and magnesium. Micronutrients help flowers grow faster, maintain a dark green color, and sprout new roots and shoots. Trace elements include the nutrients boron, manganese, iron, zinc, copper, and molybdenum. Also known as trace micronutrients, the trace elements also promote healthy, fast-growing plants with rich green colors.
Granular, water soluble, and natural organic are three main types of fertilizer. Natural organic flower fertilizer contains mostly manure and bone meal and although they are natural, they provide lower levels of nutrients than synthetic fertilizers. Water soluble fertilizer is meant to be mixed with water, and plants absorb it quickly. The drawback of water soluble flower fertilizers is that they only remain in the soil for one to two weeks and require more frequent application. Granular fertilizer is the most common, and provides flowers with nutrients for six to nine months.
Once you understand the nutrients plants need and the types of fertilizer available, you are ready to choose the best flower fertilizer for your garden. Remember that plants will not grow well with higher levels of unneeded nutrients, but will flourish if you provide them with the nutrients they lack. Checking your soil's pH levels and texture is also a good idea. Clay and sandy soils may not absorb nutrients properly, and soil that is too acidic or alkaline does not promote strong growth.