Plants need food, water, air and warmth. Sometimes the soil they are growing in lacks the nutrients they need to sustain themselves. That is where fertilizer comes in. However, there is more to it than just sprinkling a little fertilizer here and there. It is important to understand what it does and how it relates to the plants, as well as the impact the timing of the application has and any negative considerations associated with its use.
Fertilizer is used to enhance the nutrients in the soil. Plants require 16 different nutrients to grow properly but three are essential and commonly depleted by plants: nitrogen, phosphorus and potassium. Fertilizer replenishes these nutrients so plants can thrive.
Depending on the plants being treated, fertilizer can be applied at various times. For soil preparation before seeding grass or planting a crop, early spring is the best time. For established lawns, late spring and fall applications work best. For crops and gardens, spring and summer applications are recommended though not all need a summer application. Vegetable and flower gardens are a little trickier because different plants require different nutrients at different times. The same is true for house plants. It is best to check with your local extension office when dealing with gardens containing mixed plants.
Fertilizers can cause problems too. When it comes to lawns, too much can cause excessive growth, which necessitates more frequent mowing and watering. Over fertilizing or applying it inappropriately can cause fertilizer burn and plants can take on a yellow, burnt look and perhaps die if the amount is excessive.
Fertilizers typically contain nitrogen, which boosts leaf production. For lawns, this means lush, thicker grass. For other plants, it means more leaves, which conduct a majority of the photosynthesis and process food for the plant. The phosphorus in fertilizer promotes development of roots and helps plants distribute water. The potassium in most fertilizers helps flowers and fruit develop and assists in photosynthesis.
Fertilizers can either be organic or inorganic. Organic fertilizers come from living or once living things. They include animal manures, composts and plant matter such as dried leaves, straw and nut shells. Organic fertilizers are less expensive and have the added benefit of creating a good environment for organisms that live in the soil. Inorganic fertilizers are man-made and more expensive. While they can provide more exact control over the amount of nutrients being added, they can also leach into the soil and pollute groundwater.