If you've shopped for lawn fertilizer, you might have noticed a code on the label that looks something like this: NPK 29-2-4 (Sometimes only the numbers are shown). Most people ignore it, but this code tells you a lot about the fertilizer you're about to buy. The letters stand for Nitrogen, Phosphorous, and Potassium. The numbers tell you the percentage of those ingredients in the product by weight. But what do these letters and numbers add up to for the look of your lawn?
Nitrogen greens up your lawn and helps it grow. Phosphorous stimulates root growth and helps seeds sprout. Potassium helps grass withstand disease and drought. That's why Scotts® Turf Builder® Starter® Brand Fertilizer contains much more Phosphorous than Turf Builder® with 2% Iron; it helps new grass establish a good root system.
Nitrogen is Nitrogen, but where it comes from and how it gets on your lawn can make a big difference. That difference is all about how it's distributed and how quickly it's released. Bargain-basement lawn fertilizers contain mostly fast-release Nitrogen. So your lawn greens up for 7-14 days, and then the green fades away -- a feast-then-famine situation. Scotts® fertilizers use a mix of fast- and slow-release Nitrogen to help your lawn stay consistently green for 6-8 weeks.
If you look closely at most store-brand lawn fertilizers, they look like little pebbles of different colors. That's because the N, P, and K are all separate. So, when you spread the fertilizer on the lawn, you don't get an even distribution. Scotts® Turf Builder® fertilizers have "all in one particles®". So you get an even distribution of nutrients every time you apply.