Most people understand to a degree that every lawn and garden benefits from the addition of fertilizer. But many people do not know the chemistry behind that fact. What exactly is in fertilizer that makes it such a critical factor in maximizing plant health and grass growth? Lawn fertilizer contains essential nutrients that often are lacking in our natural soils.
The focus of fertilizer is the NPK ratio: the ratio addressed the percentage of nitrogen, phosphorus, and potassium in the mix (by weight). NPK percentages are printed on the bag on every bag of fertilizer you may purchase.
Lawn Fertilizer, By the Elements
This is how the nutrients in fertilizer are broken down.
Nitrogen (N) facilitates plant growth and the production of chlorophyll pigment for photosynthesis. Nitrogen is particularly important for the beginning of the growing season.
Phosphorus(P) is an essential building block of plant cells. Phosphorus also aids in plant functions such as energy production. Applied during the growing, flowering and fruiting periods, this will help produce a healthier lawn and garden.
Potassium (K) is a critical component in many grass and flowering functions such as photosynthesis and uptake of water and other nutrients from the soil. Potassium is also often referred to as “potash” when discussing fertilizers.
Understanding the NPK Ratio
The NPK ratio contained in a bag of lawn fertilizer is typically displayed prominently, and lists the percentage by weight of macronutrients contained within. For example, a 50lb bag of fertilizer with a 10-10-10 ratio contains 5lbs (10%) each of nitrogen, phosphorus, and potassium.
General-purpose fertilizers will always contain each of these three main nutrients, though not always in equal ratios. The ratio of nutrients often depends on the goal. For example, fertilizers developed for maximizing growth at the beginning of the season will have a higher nitrogen percentage, such as 16-6-4. Since potassium and phosphorus aid most in root growth and photosynthesis, fertilizers with higher proportions of these nutrients aid in increasing root production later in the growing season. Other fertilizers are less general and developed for specific plants. Be sure to check which is best for what you are attempting to grow.
What Makes Up the Rest of the Fertilizer?
Other nutrients and minerals such as calcium, copper, zinc, manganese, boron, and magnesium make up the rest of the percentage of fertilizer. These are often referred to as “micronutrients” due to the fact that plants require them in much smaller quantities than NPK. Their inclusion in fertilizer enhances plant health further and helps minimize the risk of burning. A mix that is comprised completely of NPK would chemically scorch your plants.
Which Lawn Fertilizer Should You Choose?
When you wander the fertilizer aisle of a garden center, a wide variety of ratios meet your eye. Which is appropriate for your lawn and garden? A soil test will identify a lack of any of the major nutrients, and often provides guidance to calculate how much of each nutrient is needed. In general, the average South Florida lawn benefits from 1 pound of nitrogen per 100 square feet, so be sure select a fertilizer that meets your lawn measurements if you do not wish to perform a soil test.
Understanding your fertilizer helps you treat and feed your lawn most efficiently. Use this knowledge to purchase the best fertilizer for your garden, or ask for assistance from the experts at Big Earth Landscape Supply. We are here to help to make your Sarasota or Tampa area lawn the most beautiful one in the neighborhood!