Before fertilizing lawn, take sample of soil to determine what kind to use
The other day, I was in one a local store that has a garden center and walked through to see what products it had. That way, I know which products are available for homeowners to use in gardens, lawns, shrubs and in their homes.
//
If there are products that I have recommended in the past but are not on the shelves of the stores, I need to change my recommendations.
As I was looking at the products this store had available, I noticed a man who looked confused as he walked up and down the aisle, looking at the different products. I asked him what he was looking for and he told me fertilizer for his lawn, but said there are too many to choose from.
I explained to him the different types of fertilizers, along with when and on what they should be used. As I thought about it, there are many people who don't know what's in a fertilizer, what the numbers on the fertilizer bag mean, or how much to use it on plants.
In order to know how much fertilizer to use, you need to know what nutrients are available in the soil for plants to use. The best way to determine this is to take a soil sample.
I know that I am always mentioning taking a soil sample, but this is the most important thing to do to help reduce the amount of fertilizer used. By using the proper amount of fertilizer, your plants will perform better.
The proper way to take a soil sample is to take a number of samples in an area. Take 10 to 15 individual samples randomly from the area. Take a column of soil from the soil surface to four to six inches deep from each of the 10 to 15 sites.
Mix all of the samples together, and from this take a pint of soil and put it in a bag. Bring it to the Extension office or to one of the drop-off points in Columbia County. The cost for testing the sample is $8. The results will reveal what type of fertilizer to use, how much to use, and when to apply it.
So, you have the results of your soil sample. You then go to the store to look for the fertilizer, but there are many different types. And what do the numbers on the bags mean?
The large numbers on the bag are the percentage of the three different materials that make up a fertilizer -- nitrogen, phosphorus and potassium. A fertilizer that is a 5-10-15 has 5 percent nitrogen, 10 percent phosphorus and 15 percent potassium. These numbers are important because some plants use more, or need less, of some of these elements.
So, what do these elements do for a plant?
Nitrogen is the first element on the bag and it is important in the photosynthesis process. This is why nitrogen makes the plant turn a darker-green color. It will cause the above-ground portion of the plant to grow. However, it can slow the growth of the root system.
Phosphorus is the second number on the fertilizer bag, and is important in helping the plant develop a root system. Fertilizer labeled as "starter fertilizer" will have a higher percentage of phosphorus. Flowers will need a fertilizer that has more phosphorus in it because phosphorus aids in flower development.
However, there are some plants that are sensitive to phosphorus, such as centipede and St. Augustine grasses. If the level of phosphorus in the soil becomes too high, these grasses can be damaged.
The last number on a fertilizer bag is the percentage of potassium in the fertilizer. This element is often the one most people overlook, but it is very important. Potassium strengthens cell walls in plants. This will make the plant more winter-hardy and more disease- and drought-resistant. Potassium will leach out of the soil, as will nitrogen, with heavy rains or heavy irrigation.
Understanding fertilizers is not as hard as some make it out to be. Using soil sample results, knowing what is in a fertilizer bag, and what these elements do will help you make the right choice of fertilizer to use on your plants.
Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu. The Extension Web address is www.ugaextension.com/columbia.