Lawn Fertilizer in Grapevine N-P-K
Every bag of lawn fertilizer is labeled with three numbers. Those numbers represent the percentages (by weight) of three key nutrients plants need: nitrogen-phosphorus-potassium. For example, a fertilizer bag labeled 20-10-20 contains 20 percent nitrogen, 10 percent phosphorus, and 20 percent potassium. Lawns need nitrogen for green, top growth.
Lawns need phosphorus and potassium for strong root and disease resistance. So, it this bag, there would be 20%N, 10% P, 20%K and 50% filler. If you bought 2 50-pound bags you would have 20 lbs of N, 10 lbs of P, 20 lbs of K and 50lbs of filler.
Nitrogen for lawn fertilizer comes in two forms: quick release and slow release. Slow-release fertilizers usually affect lawns for three to ten weeks. Use slow-release nitrogen during the growing season to produce steady, constant growth. Quick-release nitrogen fertilizers affect lawns in about a week.
Some fertilizer bags just show the source of the nitrogen they contain. Others go further and clearly define the slow-release or quick-release forms they contain.
Organic lawn fertilizers are gaining popularity. Most of the nitrogen they contain is slow-release. Also, the amount of nitrogen these fertilizers contain is low compared to conventional lawn fertilizers. This means you will need to use more organic fertilizer, by weight, than conventional fertilizer. For example a typical bag of organic fertilizer would be 5-3-2. A Bermuda or St. Augustine lawn needs about 4-5 pounds of actual N per year. That would mean having to put on about 100 pounds of organic fertilizer per year to meet the needs of the grass.
To calculate the amount of lawn fertilizer to put on your lawn, first determine the size of your lawn. Fertilizer application rates are based on the area of your lawn in square feet. Remember, area is determined by multiplying the length of your yard by the width.
Second, determine what type of grass you have. In Grapevine, you will likely have Bermuda or St. Augustine. There are also some Zoysia lawns and some Tall Fescue in Shady areas. Assuming it is St. Augustine or Bermuda, plan on 4- 5 pounds of Nitrogen, 1.5 pounds of Potassium, and 2.5 pounds of Potassium per year.
Determine how many pounds of lawn fertilizer you will need to apply and divide it up between treatments from around April 15th to August 15th. If you buy fertilizer that is slow release fertilizer that will release over 5-6 weeks your lawn should stay looking good and be healthy throughout the year.
Turf grass also needs other nutrients, referred to as Macro- and Micro Nutrients. Examples are Iron, Magnesium, Manganese, and others. We will address these in another article.