LawnSite Member
Ok got a question about fertilizer. What do the numbers mean on the bags..like 18-24-12. I tried searching but didn't get a very good idea on what they meant. Like one I think nitrogen-potassium-phosphorus. What would be a good starting fertilizer. Im new to everything especially fertilizer...Thanks


LawnSite Senior Member
Try doing some more searching, as the information is here. I as well am learning about the fertilizer too, before I start using it.
The numbers on the bags are as you stated N-P-K (Nitrogen, Phosphorus, Potassium). They are the percentages of each nutrient in that certain mix. So a 10-10-10 will have 10% of the weight of the bag in each of the nutrients, so 10 lbs of Nitrogen in a 100 lb bag.
There are a lot of good post on here about what each nutrient does, and when and how much to put down.
Also, what I found helpful, was going to a local nursery, or Lesco dealer, and talking to them about it.
I'm no expert on this by any means though, so hopefully some more people can help you out on this.


LawnSite Bronze Member
Georgia Z7
Twins is correct.

The numbers you are referring to are called the fertilizer ratio. Any fertilizer that has all three elements (N-P-K) is a called a complete fertilizer. Now that you understand what the numbers stand for, here is the importance of each.

Nitrogen - Provides overall turf quality. It affects color, growth and density, and tolerance to wear among other things. The amount of nitrogen needed depends highly on the turf species. Bermudagrass requires a large amount of nitrogen compared to fescue for example.

Phosphorus - Element that is normally most important during turf establishment. It helps the growth and maturity of seedlings as well as stimulating root growth. Its more for the part of the turf that you don't see.

Potassium - For overall root health and is also used to increase the turf's tolerance to extreme weather conditions. We apply potassium in the south to bermudagrass in early fall to help prevent winter kill.

The key with fertilizers is to understand with the type turf you have, exactly what is needed at that particular time of year.

Sometimes you also need a weed control ingredient as well as fertilizer. Every situation is different.