Understanding what NPK means

All fertilizer has an NPK number on the bag.  This is Nitrogen, Poshphorus, and Postassium content.  Any fertilizer ratio that is not a 4-2-1 ratio is not putting down the ideal ratio on your lawn.  Those bags are meant for special purposes when you need to additives to fix your soil.  Only buy 4-2-1 ratio fertilizer.

Some general info on how N-P-K works.  Remember, for Bermuda grass you want a 4-2-1 ratio:

N= Nitrogen   Nitrogen is the first number and it is used to green your lawn and plants. Nitrogen is needed in different amounts at different times of the year depending on the grass. It is one of the most essential nutrients of the 12 essential nutrients needed by plants and 1 of the 3 macro nutrients. Warm season grasses need more Nitrogen when it is warm and none when dormant and cool season grasses require more when it it cool. Premium lawn food is high in nitrogen, which is used to feed established lawns in their peak season (28-4-3).

P= Phosphorus  Phosphorus is the middle number which is essential for root development and creating blooms. This is a key element in helping with the development of root systems of newly seeded grass and plants. It is number 2 on our macro nutrient list and also essential for plant life. P is the key ingredient in starter fertilizer and root stimulators (18-24-12).

K= Potassium  Potassium is the last number and it is used for winter hardiness and it helps a plant survive through the cold season. It helps plants and grass develop a deeper root system, keeping the plant more insulated. You will notice that a winterizer fertilizer will have an elevated amount of K.