### What type of fertilizer should be used on lawns?

This may be rotary spreader the most difficult question to answer without a soil sample. In the absence of a soil sample, it is best to use a fertilizer with a 3-1-2 or 4-1-2 ratio of nitrogen, phosphorus and potassium. Examples of fertilizers with these ratios are 12-4-8 and 16-4-8. These numbers tell you the percentages of nitrogen (N), phosphorus (P) and potassium (K), and always in that order (sometimes referred as N-P-K). A fertilizer which contains all three of these elements is referred to as a complete fertilizer. A 100 pound bag of 16-4-8 contains 16 pounds of nitrogen, 4 pounds of phosphorus and 8 pounds of potassium. The rest if filler and minor elements. Even though it may cost more, a fertilizer containing slow release nitrogen is more efficient and cost effective in our sandy soils. A fertilizer containing one percent iron (listed on the back of container) can result in a greener lawn.

### Fertilize coverage How much fertilizer?

An almost universal recommendation for turf grasses is to apply one actual pound of nitrogen per 1000 square feet per application. To determine how many pounds of fertilizer it would take to supply 1 pound of nitrogen, divide the percent nitrogen into 100. For example: if you are using 16-4-8 fertilizer, you would take the first number in the fertilizer analysis (which is 16) and divide it into 100. Sixteen divided into 100 equals 6.25. Rounding this number to six, you would apply six pounds of 16-4-8 fertilizer per 1000 square feet of lawn area. Using 12-4-8 fertilizer, you would apply eight pounds per 1000 square feet. Using this method will allow you to apply the right amount of fertilizer without burning your lawn. To use this method you will have to determine how many total square feet you have in your lawn. The above method does not work with fertilizer applied as a liquid. With liquid fertilizers, you’re working with parts per million nitrogen-not pounds per 1000 square feet. This makes the math much more complicated. The best advise is to follow the label directions when using liquid fertilizers.

### When to fertilize?

With our warm season grasses (centipede, St. Augustine, bahia, bermuda, zoysia and carpet grasses), it is best to wait until the grass has completely greened up in the spring before applying any fertilizer. Fertilizing too early (before green up) can result in turf injury and leaching of fertilizer nutrients.

Centipede, bahia and carpet are low fertility grasses. They will grow at their best with fewer problems when fertilized only once or twice per year-once after green up and possibly a second application during the summer.

St. Augustine might also get by on one spring application; however, it is more common to apply a second application during the summer. Bermuda and zoysia will require fertilizer applications 2-3 times over the growing season. Over fertilization promotes thatch, turf decline, pest problems and degradation of the environment from leaching of nutrients that can end up in our ground water.

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