Some quick information on how to determine what the three number formulation on fertilizer bags means, and how to use the Knowledge.
All fertilizer bags come with a three number formulation, for example 24-6-14 may be what is listed on your bag… here is what it means.
The first number, in this case the 24, is the percentage of Nitrogen contained in the bag. Nitrogen is responsible for the top growth of the plant and chloroplast production that gives the plant a dark green color. So, if you were to by a 50 lb. bag, your bag would contain 12 pounds of Nitrogen. (24% of 50 lbs. = 12lbs.) Using this knowledge would enable you to know that if you wanted to apply 1 lb. of Nitrogen per 1000 sq. ft., your 50 lb. bag would cover 12,000 square feet.
Here is an excellent resource to understand and learn how to do fertilizer calculations:
Then the second number, in our case the 6, is the percentage of phosphorus in the bag. Phosphorus is responsible for seed germination and in the case of ornamental plants, it promotes strong colorful blooms. Be concerned about the amount of phosphorus you apply when planting new seeds. Rule of thumb is about 1 lb. per 1000 sq. ft. at the time of seed planting, and another ½ lb. about 2 weeks post planting. Look for a formulation called “a triple formulation” such as 19-19-19 when phosphorus is your main concern and use the same math and resource as above to calculate how much fertilizer is needed.
The third number, in our example the 14, is the amount of potassium in the bag. Potassium is often referred to as potash. Potassium is responsible for the development of roots and lateral movement, which is a fancy way of saying it helps fill in the thin gaps in your lawn. Be concerned with the amount of potassium you apply in the late spring when you plant new seeds, and in the fall. The stronger the root zone of a plant, the healthier the top part of the plant will be, and strong root systems help the plant stand up to stresses such as heat and drought. Again, use the example and resource above to calculate your potassium needs.
As always, if you have any turf questions, please feel free to reach out to me at firstname.lastname@example.org or give me a call at (317) 658-4783. I will be happy to talk turf with you anytime!