Deciphering fertilizer ratings is actually quite simple, and knowing what they mean will help you tremendously in finding the best fertilizer for a specific job. If you've ever shopped for plant fertilizer, you've most likely noticed the three numbers, separated by dashes, on every product bag. You may have also overheard experienced gardeners and landscapers refer to various fertilizers by these numbers, rather than by a particular brand name, and wondered what they were talking about and what it meant.
The first step in understanding these three numbers is to understand what element each of them represent. The numbers you see on fertilizer product bags, read from left to right, represent the elements nitrogen, phosphorus and potassium, respectively. These numbers are intended to indicate the percentage of the element the user can expect to get from the fertilizer. Therefore, a bag of fertilizer with the numbers "20-5-10" printed on it signifies a fertilizer which will supply 20% nitrogen, 5% phosphorus and 10% potassium. The nitrogen present in fertilizer is what gives plants their verdancy, strength and thickness. The phosphorus encourages healthy root growth, while the potassium aids plants in fighting weather and disease. Because phosphorus also speeds up the maturation of plants, fertilizers containing large percentages of phosphorus aren't necessary for fully developed plants.
The material which accounts for the remainder of the fertilizer left over after adding the nitrogen, phosphorus and potassium percentages together is largely organic filler material which contains micronutrients. The filler material facilitates the more even application and distribution of the nitrogen, phosphorus and potassium, while the micronutrients supply trace amounts of other elements required for healthy plant growth.
Once you know what these three numbers represent, you can more easily shop for fertilizer that is the most appropriate for the situation at hand. For example, a homeowner looking to fertilize their lawn in preparation for intense summer heat will need to use a potassium-heavy fertilizer in which the third number is either as large or larger than either of the first two. By contrast, a new lawn would require more phosphorus for optimal health. This means you'd be on the lookout for a fertilizer with a middle number as high or higher than the other two.
Lastly, gardeners and landscapers who are meticulous about what sorts of products they're using on their lawn or in their garden may want to look not only at the element ratio, but at the list of ingredients on the back of the bag. Not all fertilizers derive their nitrogen, phosphorus and potassium from entirely natural or organic sources. Some fertilizers utilize man-made or synthetic versions of these three important elements, meaning that the elements have been artificially bonded with another compound to control the release rate of the elements. While synthetic fertilizers are cheaper than organic fertilizers, this source of the main elements will most likely be of importance to gardeners and landscapers who are completely committed to organic cultivation methods.
With this guide, you will be able to buy the best fertilizer for your lawn and garden.