Fertilizer - Knowledgebase Question

Streamwood, Il
Question by ronmeinhardt
July 1, 2009
When describing fertilizers, what is the up, down, and all around rule?

Answer from NGA
July 1, 2009


There are three basic types of turf or lawn fertilizers that you will find in stores: organic, slow release, and soluble synthetic. They are not as difficult to understand as the names imply. Of these three, you probably will use the soluble synthetic type if only for convenience, availability, and price. But look over the other two before making a buying decision.

Bags of fertilizer are labeled by the manufacturer and give a basic analysis of the contents. Below is a brief description of what you'll find and how to interpret it:

The formula will be in numbers such as 20-4-8. The numbers stand for the percentage of chemicals in the content of the bag. The first number is always nitrogen. The second is always phosphate, and the third is always potash-and always in that order. It never changes.

The first number is nitrogen. It makes the grass grow green and UP. The second number is phosphate and it makes the root system grow DOWN and healthy. The third number is potash and it makes the grass propagate or grow AROUND. Thus: UP, DOWN, and ALL AROUND. You can apply it this way: If you want the grass to grow UP and green, you want a high first number. If you want to build a hardy root system, you want a high second DOWN number. If you want the grass especially newly established grass-to propagate, you want a high ALL AROUND third number. An example: 16-10-10. You will get some greening, but the roots and propagation will be the benefactors. 22-6-4. Lots of greening, some roots, little propagation. A high first number will give the grass a quick shot of green-up. (The above are examples.)

This type of fertilizer is termed "balanced." The word "balance" refers to the chemicals. Example: grass needs three to five times more nitrogen as phosphorus and twice as much potassium as phosphorus. That's why you will usually see this formula in numbers such as 21-7-14 or 24-4-8, although not always since soil and climate may play a role in the product's formula. Sometimes there will be a high first number and low second and third numbers. Or there will be a fairly low first number a high second number, and a low third number, or a low first and second number and a high third number. By applying UP, DOWN ALL AROUND to the numbers, you will know what the fertilizer is intended to do: green the grass (or plant), build the root system, or propagate it. And this is about as technical as you need to get unless you want to get into the chemical, climatology, and other elements of turf building and maintenance.

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