One company sells a bag of 21- 4-6, another a 28-3-6, still another a 29-3-4, they all come in 7, 10, 15 and 20kg bags…What A Headache! These numbers represent the percentage by weight of the major nutrients required by grass. For example, a bag of 21- 4-6 is made up of 21% nitrogen, 4% phosphorus and 6% potassium. Research shows a lawn requires about 2 kg’s of Nitrogen (the most important) per 100 m2 annually and that it never be applied heavier than 0.5 to 0.7 kg per application. A 10kg bag of 21-4-6 contains 2.1 kg of nitrogen and covers 300 m2 that’s at the recommended 0.7 kg per 100 m2. Numbers, numbers, numbers, it could drive you mad. Truth is, most quality major brands are designed to deliver the right amount of nitrogen to your lawn. However, this may not be true for less reputable brands. At Rice Road Greenhouses we make it easy by offering a high quality, 4 step customizable program that’s just right and at a great value.