What does N-P-K mean?

Nitrogen-  Phosphorous - Potassium (a.k.a. Potash)

There are 3 numbers on fertilizers or composts that correspond  to the percentage of these nutrients. 

Here is what each nutrient is good for:
Nitrogen helps plant foliage to grow strong
Phosphorous helps flowers and roots grow and develop
Potassium (Potash) is important for overall plant health

So next time your local garden store sales person says that you want to get a fertilizer high in nitrogen, make sure that your getting the one that has a large first number.

Good luck - Ask questions - Have fun!!!

Ellen- Thanks for the inspiration!!!