What do the three numbers on fertilizers relate to? If I remember correctly, one is for the roots, one for flowers, and the other for the greenery, but I forgot which is which.
Most plants feed primarily on three nutrients – nitrogen (N), phosphorous (K) and potassium (P). These nutrients are represented on fertilizer packages by three numbers. Let’s say you picked up a bag of all–purpose fertilizer. The numbers might read something like 9–15–13, meaning the bag contains 9 percent nitrogen, 15 percent phosphorous and 13 percent potassium.
Nitrogen is important because it helps with vigorous growth and produces lots of leafy foliage. It is the sort of thing, as you might expect, that would be ideal for grass, but not the sort of thing that you would want to put on tomatoes, because this would cause the plant to produce lots of leaves and not much fruit.
The middle number is phosphorus, and it is important in the production of blooms and fruit. This is useful for feeding perennials and vegetables.
The last number is potassium. This is good for strong root and stem development.