Grass Fertilizer
What The Grass Fertilizer Numbers Are All About
Don't let the numbers you see on grass fertilizer packages scare you away. There's really quite a simple explanation, and once you understand it, you'll be in a far better position to give your lawn the proper nutrition, at the proper time.
The basic component make-up in a box or sack of grass fertilizer is identified by a set of 3 numbers, actually ratios. The first number, designated by the letter N, represents nitrogen, the favorite food of grass. The middle number is phosphorus, represented by the letter P, and the final number is potassium, represented by the letter K, that being the designation for potassium in the periodic table of elements (phosphorus had already taken P).
A 20 -8- 10 fertilizer then, would have 20 parts of nitrogen to 8 parts of phosphorus to 10 parts of potassium. A 20-20-20 fertilizer would have equal amounts of each. A number can also be 0. Since grass depends heavily on nitrogen for growth, you'll usually want a fertilizer where the first number, N, is largest. Nitrogen is what gives you lush green blades of grass in abundance. Phosphorus (P) stimulates root growth, while potassium (K) is vital for maintaining healthy plants.
So when you are adding fertilizer to an established lawn, you're usually adding nitrogen. Put too much nitrogen on some vegetables or fruits, and you get an abundance of leaves, with no fruit or flowers. In choosing a grass fertilizer, you don't care about fruit or flowers, you care about grass blades, and that's what nitrogen gives you.
When you're choosing a grass fertilizer for a new lawn, you'll want one containing a higher ratio of phosphorous. You still want some nitrogen, but not too much at this stage. The role of phosphorus will be to build a strong root system, and that is more important than blade growth during the initial stage of your lawn's growth. Potassium comes into play when you are preparing your lawn for the hot summer months, or for winter, both stressful times for grass. Potassium helps the lawn tolerate such conditions and remain healthy. Fertilizers containing higher ratios of phosphorus and/or potassium tend to be more expensive. Remember you only need these for the new lawn or for preparing the lawn for extremes in climate. For the most part you're fine with the less expensive high nitrogen fertilizer.
Without getting into the details as to whether to use a chemical grass fertilizer, or an organic grass fertilizer, you can look at it this way. Chemical fertilizers are often faster acting, and in that respect can play a beneficial role. The downside is, they can also be harsh on your lawn if applied too often, or in excess. Organic fertilizers may be slower acting, and more expensive, but you want to protect the investment you have in your lawn, and slower and more expensive can often be better. If you over fertilize with a slower-acting grass fertilizer, you're less apt to have a price to pay at the end of the day.
Rules of thumb: Read and understand the labels. You want higher phosphorus and less nitrogen for a new lawn, mostly nitrogen the rest of the time, and phosphorus to prepare the lawn for changing climate conditions. And, you're better off with a slow-acting, hence longer-acting fertilizer. Don't try to short cut on cost, you'll be better off in the long run.
You can also find recipes for making your own home-grown fertilizers, or lawn "tonics" as some call them. No one is stopping you, and feel free to experiment. It's your lawn. You'll probably eventually come to the conclusion that the store-bought stuff is perfectly fine, but then again, maybe you'll hit upon the perfect formula.